Compare him to Jordan and the two are very similar. Their advanced stats in their best seasons are almost identical. If anything MJ is slightly higher in the regular season and Lebron is slightly higher in the playoffs, the opposite of what is usually assumed. But this could be a sample-size issue, or the recent trend of stars taking it easy during the regular season. Either way, they are very, very close.
They've won in different ways. Lebron was the master at taking his teams to the Finals, MJ had fewer Finals trips, but was the best at winning once there. MJ played (almost) his entire career for one team, which in the later seasons had lot of other stars playing cohesive roles. They were good without him, but Jordan lifted these teams to be some of the best of all time.
Lebron played on several different teams, most poorly constructed and/or with fewer other stars. His teams usually fell apart without him, and his biggest skill was to take any team he played for deep into the playoffs. He probably had a bigger impact on his teams, but Jordan's teams reached a higher level.
All of this feels like a wash. You may prefer one or the other, but it's very close. But here's the thing: Lebron has done this in a career that is 30%+ longer than Jordans'.
He has an argument as the greatest young player of all time
He has an argument as the greatest peak player of all time
He has an argument as the greatest old player of all time
Lebron is the all-time scoring leader, despite not being a pure scorer. He's 4th in assists and 9th in steals despite not being a guard (Jordan is 4th in steals), and 33rd in rebounds despite not being a center. He's way ahead of Jordan on every type of career value stat (some he's way ahead of everyone; Kareem is with him on a couple).
So unless you think Jordan was a WAY better peak player, which is not backed up by any stats, Lebron's longevity should put him over the top. 40,000 points would be the icing on the cake.