I like The Next Generation. I thought it had some of the best sci-fi elements of any show, movie or tv. The collectivist philosophy is of course a turn-off.
But after watching Firefly, watching the other shows is just ... watching the shows. With Firefly I get pulled into their world and I forget where I really am (my living room) until the credits come at the end. Then it's "oh yeah ... it's just a tv show".