LeBron. If for no other reason than there is a greater chance of Kobe's fallaway jumpers not going down at a high % compared to LeBron's drives to the rim. As good of a defender Kobe is, he is not stopping LeBron from getting to the rim with no help defense whatsoever. LeBron has the size, strength and speed all going for him, and it's not like the man can't shoot a jumper anymore...he's been hitting them at a very respectable rate the last year or two. Not to mention LeBron would be grabbing nearly every board on both the offensive and defensive glass, especially at this stage of Kobe's career where he doesn't have the spring to grab the 7-9RPG that LeBron can in a real NBA game.