This will probably be a debate that will rage on forever, unless Lebron James manages to be a part of four more championship games.
While the entire body of work needs to be considered, championship wins tend to trump statistics, and Michael Jordan, the other real contender for NBA GOAT, is a perfect 6-0, while James is 3-5.
And in reality, Jordan might have ended up in more, if he hadn't decided to go play baseball in the middle of his championship seasons.
He also played during an era where defensive players were allowed to be more physical, and when the three pointer wasn't in as much use as it is now. So, who knows how much more Jordan could have accomplished back then, and what he might have been able to do now.
James has the advantage of playing straight out of high school, so like Kobe Bryant, he will be able to play longer than Jordan did. If the Lakers can pull it together before James is done (if he does go somewhere else), than maybe they make another run, though now he plays in the same league as the Golden State Warriors, who may just win another championship.
There is no doubt that James has the ability to take over a game on both ends of the court, and that he is much more of a physically dominant player than Jordan was. He's also taller, so he can play at quite a few different positions on the court and creates a mismatch with virtually any defensive player.
That said, Lebron isn't as well known for his killer instincts when it comes to crunch time. He has shown up in quite a few must win playoff games, but not in all. He's had teams with very good players around him who managed to lose championships as well as win them. In some ways, he is his own worst enemy, because really, there isn't much of anyone who matches up with him otherwise.
Meanwhile, Jordan had the skill, the physical abilities and the steel will, the perfect combination for winning regular season games and winning in the playoffs. At this point, I would still pick Jordan over Lebron for NBA GOAT.