Doc Samson has punched out the Hulk. You can argue he knows his fighting style etc etc but thats definately requires alot of power. I mean didn't wrecker get knocked out by Luke Cage in his last appearance in New Avengers?
Although Samson is stronger at 70 tonnes vs the Wreckers (at fukll power) 40 tonnes, the Wrecker is a fantastic fighter with his Wrecking Bar. He has stood toe to toe with Thor. With that Wrecking Bar, the Wrcker does a lot more damage than his fists alone. How much more damage would a normal person do swinging a steel crowbar than hitting with their hand. The same applies for the Wrecker (and his bar is virtually indestructible).
I would say that their levels of durability and endurance are fairly similar. I think that the Wrecker is at least as good a hand to hand fighter as Samson (and maybe a little better) as he has been fighting (and learning) a lot longer. I mentioned it in another thread that samson knows the Hulk';s fighting style and that does provide some advantages.
Samson is more intelligent but that is not the same as battle smarts. Samson can also leap (approx 900 ft) and that could priovide some tactical advantage 9movement round a battle field)
Overall I would think that it would be a close, but I would say the Wrecker 9on his showings at full power) might pull off the win.