This is one of the most subtle, longtime-viewer-rewarding shows ever. Seriously, half the episodes nowadays are probably not even funny to people who haven't been watching for years and know all the standards and archetypes this show's set up over time.
But crap... the characters alone. Pretty much everything Dale says is funny. Hank has the best line-delivery of almost any character in television history thanks to Mike Judge. And Bill is the funniest character on the show by far. WHAT OTHER SHOW could make jokes about someone wanting to die that funny and in no way sad, until you REALLY thought about it? The time he repeatedly tried to kill himself, and went for his gun, but Dale forced him not to do it BY THREATENING TO SHOOT HIM. But even Bill gets his moments.
Who else has the balls to freely mock Asian society the way this show does, with Khan being a relentless status-chasing gloryhound who pressures his daughter into violin playing and being a Grade-A student? And the way it mocks both the right AND the left wings is great.
Other great stuff:
-Joseph going from a normal kid to a hilarious stereotype of angsty teenagers, all horny and awkward, even trying to make out with Minh.
-Dale blowing a multi-million dollar lawsuit against Manitoba cigarettes, just to win his wife's love back by admitting he really did find her beautiful after all (he was pretending she was ugly from the smoke to sue them). Beautifully sweet, but hilariously funny as he was interrogating himself ("Mr. Gribble, ARE YOU A HOMOSEXUAL?!?" Dale runs back to the chair "AAAAAAAAHHHHHH!").
-Bill sleeping with Kahn's mom, and when the Arlenites get pissy at Kahn for trying to break them up, he just gets indignant and shouts "You'd all do the same if Dauterive was nailing your mothers!" And they all just look at each other, shrug, and silently admit it.
-Hank rebuilding Bobby's wrecked Dummy into his idea of a perfect son, with Bobby & Peggy's great reactions, before finally scrapping him and making a Bobby lookalike.
-Hank speeding on the highway to go vote, and a cop pulls him over. On discovering the reason, the cop goes "You haven't VOTED YET?" Cut the police car screaming down the highway with sirens blaring, leading Hank to the polling station.
-Hell, EVERYTHING with Cotton in it. Especially the episode where he gets Peggy to walk again.