I think there should be a difference between ‘most important’ and ‘best’. I think a lot of folks just named the 5 best players.
On a list of most important, Garnett has to make the list, without him this team would be roughly 35 years without a title or even a finals appearance. If Garnett wasn’t long tenured enough for the list then you have to throw in Pierce.
My 5 most important Celtics:
1. Russell
2. Bird
3. Hondo
4. Cowens
5. Garnett
5 for the Lakers:
1. Magic
2. Shaq
3. Kareem
4. Kobe
5. Lebron
How have LeBron's 184 games for the Lakers been more important than Jerry West's 1085?
I'd go West, but I think there is an argument that but for Lebron, the Lakers might still be an embarrassment. They were an absolute train wreck before Lebron got there. All kinds of in fighting, a dispute between the brother and sister owner, a terrible revolving door at coach and executives, and not to mention losing like they had never seen. I mean they were basically the Knicks over that 5 year period. Not to mention the losing. When Lebron signed up they had missed the playoffs 5 straight years, before that run they had missed the playoffs just 5 times in the entire franchise history. They were a top 4 seed when Lebron got hurt his first year and ended up missing the playoffs for 6 years in a row. But for Lebron, they don't land Davis and don't win the title last year. Lebron basically saved the Lakers. How bad would they still be with Ingram, Ball, Hart, Kuzma, and whatever not super high lottery picks they would have landed. Lebron changed the culture and changed that team for the better.
Magic, Shaq, Kareem, and Kobe are pretty easy, after that is is much more difficult. I think you could make reasonable arguments for Mikan, West, Baylor, or Chamberlain and the best argument for Lebron I laid out above, but Lebron I just don't think has the games to be there yet (if they win another title or two and he plays another 5 years for them, then he starts to be in the discussion). I know Mikan is often overlooked because he played in Minneapolis, but he was the best player in the world on the best team in the world for 6 years winning 5 titles. Early NBA and Minneapolis so he is often ignored, but they don't have 5 titles without him.