My favourite original cable show is probably the one you've been watching: The Larry Sanders Show. Everything you said about it is right on. I also like Gary Shandling's first cable show as well, but Larry Sanders is almost brilliantly transcendant!
I love South Park. Still the most incisive, sharp, outrageous satire on TV. Favourite episode would probably have to be the Jennifer Lopez one where Cartman does a Senor Wences act with his hand as puppet Jennifer Lopez. It terrifically, courageous absurdist...first, that Cartman, a fourth grader, is doing a Senor Wences bit and secondly that the creators are doing the bit to a general audience, who like Cartman, probably would have no idea who Senor Wences is. Just wonderfully loopy.
I loved ROME.
DEADWOOD started out well, but I thought last season was the longest shaggy dog story that went absolutely no where and ended disappointedly, not taking us where it felt like it was leading up to.