I like the TOS 2-6 and FC uniforms, but my major problem: don't they get too stuffy with all those layers and thick fabrics?
Now that I think about, many of the complaints about Trek around the time of Nemesis was that the franchise was getting darker. I think it's somewhat logical to attribute that mindset to the uniforms, just as how some people thought TNG was bland simply because the bridge was beige (and hey, degrees of truthiness vary, but color theory is very real).
Prior to that, the TNG 3-7 uniforms were almost too bright. Yeah, I look back with rose-tinted glasses as I grew up with those uniforms, and the sharp shoulders and collars were simple but vast improvements over the TNG 1-2 uniforms. But there's one episode (Journey's End) where Picard, Troi, and Worf face down the Cardassians. Picking those three crewmen showed the nice variety between division colors, but the big bad and armored Cardassians in the bright and dusty desert made the Starfleet uniforms look almost childish and outdated, an opinion I had when the episode first premiered.
I do like that Generations had a mix of TNG 3-7 and DS9/VOY uniforms. It showed a lot more variety and freedom for officers to choose. But that's only a temporary solution.
With that said, I prefer the ENT uniforms, though that could just be my 21st century biases coming in. I'm starting to like the ST: Online uniforms.