As a Sith, I would opt for a matching pair of curved-hilt deep red lightsabers. No sense breaking tradition, and, besides, who has time to worry about the color of your lightsaber blade when your only interest is in slaughtering as many people as possible with it? However, I would also carry several lightsabers from Jedi I had killed, so I'd probably wind up using several colors. Assuming I'm any good with a lightsaber in the first place, I'd have a nice collection.
Then, at retirement age, I would set up a shop on Korriban: Imp Spittle's Used Lightsaber Emporium. I would sell off my old lightsabers to Sith trainees and wannabes and watch them clumsily slice themselves in half out on the streets of Dreshdae.
If in the shoes of a Jedi, I'd probably go with the boring old green or blue (more likely blue). I'm really not picky about the color of my lightsaber, because, as stated once already, I'd be more concerned with proficiency with the weapon rather than appearances.