It really is a tough argument all around. I think if we were to go by individual accomplishments, you have to go with Cousy, Havlicek, Bird, Cowens, and Russell. With that, you have the only 4 players to win the MVP award and with Hondo, you have the C's all time leading scorer and one of the best players on both the Russell and Cowens title teams.
If you were actually talking about what would be the best Celtic starting lineup from an actual playing standpoint (like if you had a time machine or were playing a video game) I might sub in McHale for Cowens. Both were great scorers, but McHale's out of this world post moves might end up being more helpful next to Bill Russell, who for as great as he was, wasn't an elite scorer, particularly in the post (more of his scoring came from running the floor, put backs on rebounds, and open shots--sort of like Cowens).
So first team
Russell
Cowens
Bird
Havlicek
Cousy
Second team
Parish
McHale
Pierce
Jones
White
Rounding out the bench
Heinsohn
Johnson