I'd say:
Korriban > Ord Mantell > Tython > Hutta
Korriban - "Korriban. The birthplace of my power." You really get a feeling of the Sith legacy here. I thought the color choices were a bit of a strain on the eyes at first, but it grew on me. Also a good callback to KotOR.
Ord Mantell - Feels like a warzone the minute you step outside. Gives a good military vibe for the Trooper and a sense of purpose/revenge for the Smuggler.
Tython - Beautiful looking, my favorite of the forest planets. Tranquil, as expected of the Jedi world, though it is a bit of a pain to travel.
Hutta - Too much backtracking for my taste, although I will say that the Hutts vile-ness is really shown here.