I've seen both their careers in full (obviously, Lebron's is still going). It's Bird all day. I just don't understand the debate.
I'd give the edge to Lebron in athleticism and the fact that's made him a top defender in both individual and team defense but that's not nearly enough to put him ahead of Bird. Bird's offensive skills are so far beyond Lebron's. Sure, Lebron can charge into people, palm the ball, travel and get all the love of the officiating crew to look great but Bird didn't have that to inflate his numbers.
Bird's passing was second to none for a forward and I would argue second only to Magic during Bird's career.
He's a far superior rebounder---knew where to position himself and how to box out-->didn't need to rely on athleticism to get the boards.
His team D is incredibly underrated and he wasn't as bad as people think when it came to individual D. Not as good as Lebron on individual D, but solid.
Sure, Lebron's been miraculously healthy for his career which is admittedly an accomplishment considering his style of play but I don't see that as a big factor in this debate. Sure, if Bird only played 5-6 years, that would be a factor but he played for a longer time than that.
Lebron's a great player, best in the game for quite a while now, no question. As much as I don't like him, he's one of the best ever. But he's not as good as Bird. I watch him and just don't see the skills that Bird had.