Well, it depends what we are talking about. I wouldn't consider Simmons a celtics sports writer. He is a national columnist (blogger, whatever you want to call him), who happens to be a fan of the celtics. He does not have the access and insight that the beat writers and local columnists do. He does a great job giving the fans perspective (even if I don't always agree with him), but I don't think he fits in the same category.
Here is mine:
1. Jackie McMullen - She doesn't write about them nearly enough anymore, but when she does, its almost always a must read.
2. Marc Spears - He is the best beat writer the Celtics have had since Michael Holley. For the first time in a long time, we are actually getting insight into what is going on. He seems to know, and love the game, and really works his connections to bring news to the fans.
3. Bob Ryan - He has lost a bit off his fastball, and I think being on these TV shows has pushed a little too far into the "say stuff just to make headlines" territory...but he still pounds out several masterworks a year, which no one on this list can contend with, except McMullen. He is kind of here by default.
4. Steve Bulpett - He is the definition of mediocre. He reports what's happening, but doesn't bring anything special to the table. The strange thing is when I hear him on the radio or TV, he seems to actually have a lot of good information, is incredibly funny (in a dry, sarcastic sort of way), and is a real sports historian...but he somehow fails to bring this to his writing.
5. Shira Springer - She still can write a mean fluff piece.