Generally Americans. I can easily rattle off at least a dozen American sitcoms I love, and I couldn't give you half that number of British shows. There's a very sharp, broad, scripted quality to my favourite sitcoms (say classic era Simpsons) that, while some British shows come close to it in terms of style, few really equal. Granted, there's a bias in being exposed to so much British TV, a great deal of which is truly awful... while not seeing the worst say American TV has to offer. In short: Red Dwarf gets a couple of laughs. But I can't think of an episode of that show I've loved as much as Futurama's "Roswell That Ends Well." That's an interesting because I'd consider it a very American sitcom (even with Jane Leeves). Very much Three's Company with erudite references... and essentially it takes Cheers's slobs vs. snobs humour and just chooses to centre on the snobs instead. It doesn't much resemble most British sitcoms I've watched.