I'm going with Lesnar on this one....although like MTJ stated, if either man connects it could be over very quick. When you are that big and strong and talented, it could just be a matter of who hits who first.
Lesnar looks to be in phenomenal shape though by viewing him on that Randy Couture youtube video that is currently up with them training with each other. Brock looks lighter and leaner and much quicker.....well, on that video at least
Carwin is definitely the the most physically strong guy that Lesnar has faced. He won't be able to so easily throw him around like he did his other opponents. But, I still think Lesnar (at least before his medical issue) is the stronger guy. Carwin is the technically superior guy, probably some of the best technical boxing skills in his division. But, what I don't think Carwin has is Lesnar's speed.
* Technical Striking
* Knockout Power
Although, it's anyone's guess how Lesnar will perform now post-illness. It's possible he's lost some of that speed and strength.
Could go either way, but I do think that right now Carwin has the best chance at taking out Lesnar. I do hope Carwin wins. He's a humble, intelligent guy and helps bring a positive image to the sport. Lesnar is and has been doing the opposite, I think.