i adore JUSTIFIED because it's essentially a character-driven comic book saga with a rich history/mythology driving it, plus most of those characters happen to be awesome. that kinda thing is just catnip for me. and yeah, the first season is more light-hearted and episodic and not really representative (though still fun), second season is where it comes into its own. i think it pretty clearly stands out from the usual TV detective dross, although obviously it isn't a stunning work of art like DEADWOOD or w/e.
it's pretty gay. it does have its great moments though, and more natural conversation than basically anything else that had been shown on TV up to that point.
ok, i'll make an effort:
CARNIVALE is widely regarded as a quality show, got cancelled early though.
BORED TO DEATH is supposed to be good. if you dislike zach galifianakis and jason schwartzman you should probably avoid.
ROME is well above average for what it is, JOHN ADAMS supposedly is too.
if you want more stuff like THE WIRE (or by THE WIRE people) there's TREME, THE CORNER, SHOW ME A HERO, GENERATION KILL etc.
i personally really enjoy IN TREATMENT starring gabriel byrne (and a lot of strong performances, including breakout roles from the currently hyped likes of mia wasikowska, alison pill, dale dehaan etc) but it's pretty gimmicky (every ep is a therapy session) and you might hate it. it starts with by far its best season though.
JOHN FROM CINCINNATI is reputedly an oddball classic from the creator of DEADWOOD. LUCK is also a show by the DEADWOOD creator which, predictably, got cancelled before it was completed.
EXTRAS is the best thing ricky gervais ever did, worth a look even if you aren't a fan 'cause the way it shits on some of the guest stars is priceless.
some other stuff that's got a good reception: ENLIGHTENED, EASTBOUND & DOWN, VEEP, SILICON VALLEY. i haven't seen any of these though.
oh and there's OZ if you're not aware of that. i'm not a big fan from what i've seen (too many overtly thematic eps: the Faith episode, the Racism episode, etc, all very on-the-nose) but it's generally regarded as one of the precursors to what HBO dramas would eventually become.