1) Enterprise: They look like uniforms. Practical, no too colorful, like something real life astronauts would wear.
2) DS9/Voy: Nice, comfortable looking, and the sciences decision had the nicest blue-green of any ST uniform ever.
3) TNG Seasons 3-7: Nice, exotic, yet serious looking, nice color scheme (except for science/medical that bright teal looks good on nobody, it's a wonder Gates McFadden was able to pull it off so well)
4) TNG Seasons 1-2: The science colour was darker and more greenish in this which imho looked better on both Gates McFadden and Marina Sirtis. Curse them for never putting Marina into one of the early uniforms after the pilot! The scant was okay in Season 2 when it was worn with pants and I admit I would have liked to see Brent Spiner in one of them, it would have also been perfectly in-character for Data.
5) The WOK-TUC movie uniforms. The only uniforms that actually look somewhat military. They looked a bit warm and they could have chosen a nicer color scheme, but they were definitely an improvement over the TMP uniforms and even more so over the TOS sweaters/GoGo dresses.