I always did like Kirk's uniform in Star Trek: The Motion Picture

(via Memory Alpha)

The TMP uniforms were pretty swanky and well, let's face it, fit the polyester era of science fiction perfectly. The uniforms were apparently one-piece, which I imagine was a pretty annoying thing when you needed to use the bathroom or just changing in and out of.

(via Memory Alpha)

The sleeveless version was pretty cool as sort of a "casual-wear" uniform. It looks like this one might not be a one-piece, but the hem of the tunic might just be hiding it.