A lot of players like to live in (or are from) California.

I think a lot of it has to do with the weather being nicer in the west. Also generally speaking, I feel like for what ever reason, owners/management is better in the west.

It's not. The 90s was basically ruled by the east. A good chunk of the 80s too. These things go in waves.

The Bulls ruled the 90s but, 7 of the top 10 teams as far as wins go where in the west. Between the 1989-90 and 1998-99 seasons. 

I don't think there's an actual reason, but as other said, it goes in waves - I can add my 2 cents by saying maybe taxes can help in favoriting some states over others

I was going to mention the Bulls, but it kind of goes without saying that they were different.

Weather is nicer out west as other have said so they have an easier time with free agents. Not as true recently but west owners were much better for a while too but that might just be by chance. Other people says it goes in waves but it’s been pretty solidly west the last 25-ish years and the league has matured enough from the old days I don’t think it’ll have a major shift anytime soon.