My favorites are Bartley's (don't miss the onion rings) and the Bristol Lounge at the Four Seasons (funny, since wideman loves the Bristol Lounge but not Bartley's!). If you're a big fan of a big ol' hunk of meat, some people love R.F. O'Sullivan's, in Somerville, but I prefer the smaller (but not small) patty served at Bartley's.