This is a hard one, simply for the fact that both of these armors are designed to take on beings that are far beyond human strength. There have also been multiple versions of the Hulkbuster, so its hard to nail down exactly who would win.(My information on some of these events are extremely lacking. If anyone has any more info once this answer is posted, please feel free to leave comments and I will update accordingly)Let’s take the strongest form of the Hulkbuster armor, the Hulkbuster Mark II used in World War Hulk (at least my suspected strongest form, the Internet is pretty unclear about how much each model can actually take):This bad boy managed to fight Hulk to a standstill while in his Green Scar form, and would most likely have won if he’d been able to inject Hulk with the nanites that were supposed to suppress his gamma creation, however, someone had stolen the nanites, meaning nothing was being injected when he stuck Hulk with the needle.EDIT: After a long hiatus on this answer, Ben Nelson has corrected some of my incorrect assumptions, and made me redo the math :P Thanks Ben! XDI will leave the original World Breaker Hulk calculations at the bottom for anyone who still wants them.Now that we have the CORRECTED greatest guaranteed feat from Green Scar Hulk, here we go.Greatest feat: Punched Sentry hard enough to break his nose and crack his facial bones, destroying a large high-rise in the process.The building in question is shown here first:Here is the building from a better angle after Sentry uppercuts Hulk and obliterates the building:So yeah, we are looking at an estimated 10 story building, guessing an apartment complex (I am assuming some floors were cut off in that last page, simply because it is rare to find a 7 story tall building).So, as I said in the original answer, this will require a LOT of assumptions, but here is my best guess:Typical slab/floor thickness in buildings?Generally speaking a concrete residential highrise is 7-8" slabs, office are 9-10" and hotels somewhere in between.Per Coldrsx on the above website.So, we are going to be dealing with steel-reinforced concrete in 8? slabs for this answer, as this is the common construction technique in New York.https://shop.iccsafe.org/media/w...Based on this handy PDF, we can guess they are using concrete equivalent to what they call “reinforced steel beams, slabs, columns and walls”. The psi strength is rated between 4000 and 7000 psi. We are going to go with 5500 as an average on a beam that is 6 inches wide. Based on fractions, we can calculate the psi for our residential thickness slab to be about 7333 psi (I know this isn’t perfectly accurate, this is just REALLY estimated).Using this number, we can estimate how much force was produced by the SHOCKWAVE of Hulk’s punch. We will take half the force required as Sentry was flying at him at a high speed, and we can assume Newton’s third law:For every action there is an equal and opposite reaction.Newton's Three Laws of MotionThis resulting answer does NOT take into account the difference between the punch and the shockwave in force, simply because that is some SUPER complex math that I do not currently know :PThis is also striking force more so than lifting, something I hadn’t thought about when I first wrote this answer.Assuming Hulk landed approximately in the middle of the building, so the fifth floor (assuming he fell through one or two when he hit), and estimating the width of the building based on the average New York City block (as seen, it has roads running along each side of it, so we can estimate based on it’s approximately square shape that it is 264 ft. square. City block - Wikipedia), we have a surface area of each floor is about 69,696 feet square, or 10,036,224 inches square.Here is an image of basically how the shockwave is expanding inside the building:The shockwave is spherical, and it is expanding within the building, as we can see the sides are bulging out a bit too.Going from here, we can use our previously calculated force to calculate the overall shockwave’s power.The actual sphere’s diameter is about 264 feet wide, since it reaches the edges of the building. The disk area of the EXPLOSION on the fifth floor is then 7,833,219.84 in^2.The area on the sixth floor is 7,697,571.84 in^2.The area on the seventh floor is 7,471,491.84 in^2.The area on the eighth floor is 7,154,979.84 in^2.The area on the ninth floor is 6,748,035.84 in^2.The area on the roof (tenth floor) is 6,250,659.84 in^2.Basically, Hulk had to punch Sentry with enough force that the shockwave still had enough energy to break the roof’s area AFTER going through the other four floors between the epicenter and the roof. Taking that idea, we get:Force at the 10th floor had to be greater than approximately 45,836,088,606.72 lbs., or 22,918,044 tons.Force at 9th floor had to be greater than about 49,483,344,174.84 lbs. or 24,741,672 tons.Force at 8th floor had to be greater than about 52,467,467,166.72? lbs. or 26,233,733 tons.Force at the 7th floor had to be greater than about 54,788,449,662.72 lbs. or 27,394,224 tons.Force at the 6th floor had to be greater than about 56,446,294,302.72 lbs. or 28,223,147 tons.That means, BARE MINIMUM, Hulk produced about 259,021,643,913.72? lbs. or 129,510,821 tons to destroy the building as shown. Now, the margin for error is HUGE on these calculations, but the essence is still there. And this would match with his other feats, namely his fight with Iron Man:Bringing down the Sentry’s Watchtower (Location) (also known as Stark Tower) and cracking the earth.Of course, these are just the SHOCKWAVES that were produced. Upon impact, Green Scar’s fist would’ve had to have been moving supersonically and strongly to PRODUCE that shockwave. That is a whole other set of calculations that I’m not wanting to get into though, but it is safe to assume that only a quarter of the force in the impact was converted into that shockwave. Most of it was converted to heat (hence, the “explosion”), but that means Hulk probably punched Sentry with over 1 TRILLION lbs. of force, or about half a billion tons. If not more, depending a lot on the thermodynamic properties produced during impact.But suffice it to say, Hulkbuster had to be competing with that sort of energy to fight Hulk.It also had to be moving beyond supersonically to be able to keep up with him, possibly even hypersonically.Those are the feats of the Hulkbuster Mark II.Sources:what's Hulk's greatest feat of strength/power an' durability - Hulk - Comic VineIron Man's armor - WikipediaWorld Breaker Hulk ‡ The Immortal Iron HulkThe Incredible Hulk vs. The Invincible Iron Man (World War Hulk)(Again, I apologize for all the assumptions, I am trying to be as realistic as I can be. And any comments or info would be appreciated)Now lets move on to the Thorbuster:A combination of Tony’s tech and Asgardian magic and armor, this suit was designed to go toe-to-toe with the SkyFather form of Thor, his strongest form in which his strength is multiplied innumerable times. And it managed to hold Thor off while the rest of the Avengers got Asgardian gear. He did eventually lose, but not without a good fight. In his base form, Thor can move billions of times the speed of light, can lift over 20 planets of Earth’s size, has lifted the Midgard serpent with a fishing rod, and tanked the impact of a neutron star.What are some noteworthy feats that Thor has done in the comics?SUPERHERO FEATS: ThorThat means he can lift over 2.634x10^26 in his base form just on the planet feat alone, and as someone has pointed out, the Midgard serpent can be assumed to be coiled around the Earth, meaning it had its muscle strength resisting Thor. Based on the Anaconda, the heaviest snake in the world, it can constrict to over 16 times its own body weight in strength. Assuming that multiplier (I would imagine the Midgard serpent would be higher but we just have no idea how much it might be), that means Thor lifted over 105 sextillion tons of force!!! Not bad for just base form him!:Thor's Greatest Feat of Physical Strength Made Even Greater - Thor - Comic VineNow, note that these are in his BASE form. We really have no idea how much his multiplier is in that form. So it may or may not be up to millions of times more powerful or it may just be a few hundred. We just don’t know.What I want to point out is the speed though. Thor moves BILLIONS of times the speed of light with Mjonir. And he was fighting Iron Man at those speeds. Which means the suit is capable of it too.While Iron Man did not win, the fact he managed to keep up with Thor is beyond impressive.SOOOOOOOOOOOO on to my final answer!!!Who would win between the Hulkbuster and the Thorbuster?Hulkbuster is completely outmatched, unlike my original answer that placed it as a close one (thanks Ben!). It is only hypersonic, where as MINIMUM the Thorbuster would have to move near the speed of light to be able to match Skyfather Thor. Thorbuster also has to be significantly stronger. Considering BASE Thor can lift entire planets, Skyfather Thor is even stronger, meaning the suit has to withstand and give back just as much. It is powered by an Asgardian power crystal too, which gives it a massive leg up on the Hulkbuster as well.So the final verdict is Thorbuster would get a handy win over the Hulkbuster. While both are massively strong and tough, the Thorbuster faced a far tougher faster, and stronger opponent than its Hulkbuster cousin.Either way, these are far more impressive pieces of armor than people give them credit for, since they were eventually beaten. The fact Tony even managed to build tech that could get to these levels of destruction is pretty darn impressive if you asked me.Note: Thank you to all upvoters! I worked very hard on this answer, so I appreciate them a lot!EDIT:Here are the original calculations and assumptions for World Breaker Hulk:That means this armor was hitting and taking hits from a character who literally blew up a planet when he was fighting Red She Hulk just from the gamma-energized sonic boom:Yes, that’s them colliding and destroying a planet. I can’t find any info on how big the planet actually was, but I’m going to lowball and go with Earth-sized (that planet looks way bigger than that, so please bear with my assumptions). Assuming just Earth size, that means they had to together produce 2x10^32 Joules of energy at a MINIMUM.Source:How much energy would be required to destroy the planet?Since Hulk won, we can only assume he probably produced more of the energy than Red She-Hulk, but we will just go with perfectly one half to low-ball it. That’s 1x10^32, or 1 with 32 zeros after it. That was Hulk at his MAXIMUM. Now, Iron Man’s Mark II Hulkbuster armor did not fight him at that full potential, but considering the fact he lasted the longest out of the Illuminati and nearly managed to put him down, this suit is pretty strong. Let’s just assume Hulk while fighting Iron Man was using a tenth of his full assumed potential. That’s approximately 1x10^31 (wow one zero removed! Score!). Potential energy is given by E=mgh. Assuming Hulk’s lifting stance would lift an object up to about 25 ft (according to my research he fluxuates between 15ft and 25 ft, so we will say he is about 20 ft tall and lifting something over his head will be 25 ft, just for assumptions). So our equation is 1x10^32 J = m*(9.8 m/s/s)*(7.62 m). That means his lifting mass is about 1.34x10^29 kg, or 2.95x10^29 pounds. That's SEXTILLIONS of tons. More specifically, it is 295,275,590 sextillion tons!!! So yeah, this Hulkbuster armor was taking hits from that level or below…and SURVIVING and GIVING just as much. A rocket-propelled punch from this suit could throw Hulk as far as 7 miles.