There are really only two categories I can see in which Lebron has beaten Bird for his career and they are PPG (+12%) and Free Throw Rate (+100%).
Bird on the other hand has beat Lebron in rebounding (+40%), three point percentage (+3.5%) and FT% (+14%).
So since Bird has won three categories to Lebron's one, I would give Bird the winner of the "tangibles / stats" category.
As far as intangibles go, there is no competition. Bird was tougher, had higher basketball IQ (IMO), was more clutch, was a better leader, and was an absolute master of the mental game (i.e. taking opponents mind out of their game and letting them beat themselves).
There are going to be valid arguments to be made in both directions, but here is the thing that seals the deal to me - Bird did EVERYTHING well. He had no weakness in his game. He could score from anywhere on the court, he could rebound at an elite level, he could pass at an elite level, he could defend at an elite level (and did, consistently), he had leadership, he had toughness, and he is one of the greatest pure shooters to ever live
Lebron is great scorer but isn't as skilled a scorer - he's merely above average (rather than great) as a shooter and rebounder, he lacks toughness and leadership, and his defensive effort is too inconsistent.
If I'm building a team today with the choice of 30 year old bird or 30 year old Lebron (assuming both healthy) I'll take bird without a moment hesitation.