Edit: I can't believe I forgot Baskets. That show is a masterpiece.

There are a few shows I'd rate higher: Breaking Bad (although it had it's share of 'throw away' episodes), Reservation Dogs, Battlestar Galactica (so many throw away episodes), The Newsroom, and Deadwood. I think Deadwood would be my highest ranking, especially for writing and acting.

Obviously I'm sure plenty of examples can be given for why Six Feet Under is better than each of the shows I've listed, but that's the beauty of subjective lists!