Pierce>KG>Rondo>Perk>Doc
Pierce- A clear Celtics legend.
KG- Completely changed the culture and left his mark in Celtics history (albeit for not as long as Pierce did).
Rondo- Had some insanely high highs and his best moments in green. The "cult classic" Boston Celtic, if you will. I honestly think he was a decent leader here after the KG/PP Era, but his skills had deteoriated so much due to the knee injury. Guys like AB still talk about him as a lasting influence. Overall, a fun career in green that at least gave us something to talk about on the slow days.
Perk- I get the love for him, but he was never a factor as big as the other three basektball-wise. Also, his actions recently have soured my opinion of him ever so slightly.
Doc- My least favorite because he left under contract. Rondo did too, but that was pretty mutual, with the Celtics acknowledging his fall from grace and desire to go to a contender. Doc, however, was clearly still a big commodity who threw the team into lots of hoopla due to his personal desires. zi understand the guy's decision, but I still root "against" him for what he did.
Ray Allen I am indifferent towards. He left during free agency, and he was a big piece of the '08 team. However, he never felt part of "it" to me, and I'm still sour from his shoddy last playoff run with the team. His leaking bad stuff to the media was not too heroic either, but I can sort of see where that's coming from. Overall, though, I never had enough emotional connection to him to really feel super strongly when he left (after the initial bad feelings, of courss).