well seems like the original question was geared towards national telecasts but a lot of us in the states have a preference for the local broadcasts. my opinion of the local broadcasts:
Atlanta- pretty decent. I like when they put Nique on there although his mic skills are a little lacking. i love the arena announcer (J-J-J-J-Joe Johnson for thrEEEEEEEEEEEE!!!)
Boston-

to Heinsohn. Gorman is okay. i hate the way the arena announcer announces the celtics names when they make shots.
Charlotte- I liked Dell Curry as a player so i like him. the other guy is okay.
Chicago- not the biggest fan though it isn't the worst. see: Boston (wasn't this guy in NBA Hangtime?)
Cleveland- jesus almost as bad as Boston. commentators put me to sleep. and the guy that's not the play by play guy bugs me. i don't like their arena announcer either. sounds like the wizard of oz or a robot
Dallas- haven't seen to much of them. they're pretty generic
Denver- don't really remmeber them too well.
Detroit- they put me to sleep just like Cleveland's broadcast. the arena announcer is the most annoying in the NBA (DEEEETROIT BASKETBALLLLL)
Golden State- the CSN broadcast is okay.
Houston- don't think Bullard or Drexler are that good, but i guess it could be worse. arena announcer is interesting. he sounds angry a lot. i liked the way he said trevor ariza and yao ming's names
Indiana- does Clark Kellogg still do their broadcasts?? he bugs the crap outta me.
Clippers- I never really liked Ralph Lawler until recently because i get to see how bad the lakers broadcast has become. being in the LA market, i have come to appreciate Lawler's BINGO!s and his stupid Lawler's Law (1st to 100 wins the game). his partner mike smith i hate. arena announcer is boring
Lakers- Joel Meyers replaced Paul Sunderland (a volleyball announcer who replaced legendary chick Hearn after his death) and pushed his way onto TV after being an unknown radio play by play man. he bugs the shit out of me. partner stu lantz has been terrible ever since chick's death. chick obviously kept him in check. now he says dumb stereotypical black phrases like "That was NOOOOOOICE!". their long-time arena announcer is cool. kind of a deep voice.
Memphis- slightly annoying with their southern accents
Miami-nothing really makes me like them, but i guess they're middle of the road quality-wise. i like their arena announcer (Dos Minutos) and the way he announces dwyane wade
milwaukee- i think their broadcasters are pretty decent.
Minnesota- haven't seen them much, but pretty generic
NJ- pretty sure Marv still does their broadcasts and he's good. ian eagle is pretty decent too. doesn't the czar show up on there too? i've learned to like him
NY-Breen' seems to be next in line to replace Marv as top play by play man whenever Marv decides to give it up. Clyde Frazier seems like he doesn't know what he's talking about half the time lol. i think of him and i think of his quote from the hair club commercials... "no play for Mr. Gray!". i like the way the arena announcer says Gallinari
NO- don't really like their broadcasters but i like the WOOOOOs for Chris Paul in the arena
OKC- grant long is annoying.
Orlando- isn't matt goukas on there? i liked him on NBC. i recently saw a vintage orlando game and they still have the same arena announcer who i like when he says "jameeeeer nelson"
philly- pretty generic csn broadcast and boring too
phoenix-generic broadcast. their local channel has crappy on-screen graphics
portland- they're okay. the on-screen graphics are weird and take some getting used to.
sac- i like their on-screen graphics. announcers are better than most, but not great.
san antonio- jesus sean elliott is up there in homerism with Heinsohn. their broadcasts are filled with "timmy this" and "timmy that"
toronto- don't they have matt devlin? i like him and isn't he on TNT come playoff time?
Utah- they're okay. i liked the way the arena announcer used to say carlos boozer
washington- yet another generic & boring csn broadcast. although out of all the csns they are probably second to the warriors.