I'll take an Enterprise flight-suit.
TNG uniforms from Season 3 onwards come a close second in my affection.
If I were to design a new one, I'd go with the Enterprise pattern but add Gold and Red variants, to complement the Blue. Keeping the black button shirt underneath. The overall shades for each department would have to be a darker colour, so the shoulder bands still stand out. A problem encountered by the costume designers, which meant Sciences crewmen had to be represented by an olive band.