If I were Lebron, I'd be very tempted to return to Cleveland. What better stroke of ego than leaving a 2-time 60+ win team, watch them fall to 19 wins and 4 straight putrid seasons (while you take another team to 4 straight finals), return, and lead them to the finals.
Throw in the fact that's it's his hometown as a bonus.
And, in his ego driven world, how much other players are a factor in "his success" is irrelevant.