Some of the American ones I also like (and liked) a lot:
Mad About You
The show about Paul and Jamie and their dog Murrey living in NY, getting into little newly wed couple spats and having issues with cousin Ira and other friends and family. And then having a child. It was cozy rather than laugh-out-loud funny, and very very few of those lessons you were supposed to learn after watching an episode of certain sitcoms. You know, where someone has a serious moment at the end that gets resolved and the fake audience goes "aaaawww". Mad About You also did some very good crossovers with other sitcoms. Ursula Buffey (Lisa Kudrow), Phoebe's twin sister from Friends for example. Plus, Helen Hunt and Paul Reiser had good chemistry. I hope they pick the show up again, as rumor has it.
Ursula Buffey (Lisa Kudrow) was a waitress at Riff's restaurant where Paul and Jaime used to eat a lot. She's of course the twin sister of Phoebe Buffey. So when Jamie showed up at Central Perk and saw Phoebe, she thought it was her ditzy sister. Before Paul and Jaime moved in together, he used to live in Kramer's old apartment, opposite Jerry.
This is a fan made video of both the crossovers and when one of the actors plays another character. Courtney Cox didn't play Monica on Seinfeld, and Jason Alexander didn't play George on Friends. And George is, of course, horrified to be forced to watch Mad About You with fiancé Susan. This clip is very clever:
Dharma and Greg
Two opposites attracts. Old theme, but often tends to work because there is an unlimited amout of situations that can arise when two different cultures meet. I know many disliked it, but I didn't. I especially loved Greg's very up-tight mother Kitty Montgomery played by Susan Sullivan.
Full House
Does it count as an 80s sitcom or 90s?
That 70s show
Still hippie crackin' funny. The Big Bang Theory has got to have had Fez in mind when creating the character of Raj.
Friends
The only thing I disliked was the Ross & Rachel will-they-won't-they storyline. It was so boring.
Everybody loves Raymond
And everybody on the show was funnier than Raymond. But that's okay, he was the Jerry Seinfeld character of the show.
Frasier
The smartest 90s sitcom of them all. Niles and Frasier were such snobs without realizing it.
Seinfeld
The best one of all.
I don't know how many times I've re-watched it.