TOS: Haven't seen it all, but the James Blish novelizations of the series all rock, without exception. Outstanding work.
TNG: Saw it all. Much corniness. Much good. Borg. Best characters (Data, Geordi, Ro Laren... mmmm). Wimpified Borg. 'Nuff said.
DS9: Saw it all. Much less corniness. Much more good. More realistic characters (they get into fights with each other). Dominion War. 'Nuff said.
VOY: Saw first season or two, and some scattered episodes. Started out good. Continued to wimpify the Borg. Can't say much else.
ENT: Saw it all. Promising premise. Didn't deliver in seasons 1 & 2. Season 3 much improved, but still didn't take advantage of prequel opportunities. Season 4 (minus last episode) rocked to no end.
And to continue the trend:
BSG: Seen it all so far. Unlimited and unbeatable rockage. All our base are belong to Cmdr. Adama. Every character (except - intermittently - for Dr. Baltar) rocks. Season 1 Episode 1 won a Hugo. Will actually spend money to buy on DVD. 'Nuff said.
Star Wars: Seen them all. Solo ownz. 4-6 rock. 1-3 aren't worthy of the name. Jar-Jar can be blamed with the rise of the Emperor. Timothy Zahn rocks.