I'd definitely have to say between Farscape - Stargate and Stargate Atlantis. Lexx was cheesy, but pretty freaking funny too back when it was on. OH!!!! But I forgot one of my all time fave's - another by Roddenberry...ANDROMEDA!!! Damn I loved that show.
Same, the idea that the human was the alien is unique to any sci-fi series that I'm aware of, at least something that was main-stream and popular.
in some ways babylon 5 could be lumped here as humans were often seen and treated by the others as the "aliens" (especially with Kosh teaching Sheridan) it is just harder to see since the "story" was told most often from the human point of view.
It's Battletech for me. Star Trek is actually second place, but there are neat things about both.
Battletech seems more realistic, to me anyway. No aliens, just mankind and its usual petty power struggles and BS wars. There are no 'good guys', just shades of grey. No one's truly clean, but some are more admirable than others through their actions. The technology is almost all stuff we have today, only on an extremely refined level.
Star Trek, however, is the sort of series that allows one to have great hope for the future of mankind; a little hope that we might unite as a race, and overcome the stupid problems that plague our world today, and turn our attention outward.
For me, it has to have a great sense of humor, and some wonderful quotes. And with those two series, I could sit back with my friends and we could just shoot quotes back and forth remembering all the great parts of the series.
"Only one human captain has ever surivied battle with the Minbari fleet. He is behind me. You are in front of me. If you value your lives., be somehwere else"
"Why do your people always ask if someone is ready right before you're going to do something massively unwise?" "Tradition."
"Mercy is the mark of a great man." *stab* "Guess I'm just a good man." *stab* "Well, I'm all right."
"We gotta go to the crappy town where I'm a hero."