Like somebody else said, it all depends what you're looking for. Al Forno is an old standby. I'm a big fan of Cook & Brown, Farmstead in Wayland Square, Nick's on Broadway. I have to plug this new-ish place North in Luongo Square on Federal Hill. A really cool Asian spot reminiscent of Mission Chinese or Momofuku in NY.
It's a really great food town. A word to the wise: a lot of those red sauce joints on Atwells are coasting by on nostalgia at this point.