Considering he's Sith
[Noka Bibla], I'd say use the red one.
A la Darth Vader, Darth Maul, Count Dooku and so on.
The 'good guys' use blue and green, though I I'm not sure about the rules as to which are for the masters and padawans. Probably green for master Jedi and blue for the padawans.
The only purple lightsaber in the movies was used by Mace Windu:
There is no mystical significance in the color of Mace Windu's lightsaber. Samuel L. Jackson, after a jokey conversation with stunt coordinator Nick Gillard, asked Lucas if he could have a purple lightsaber and 'George Lucas' agreed.
Other colors were never used in the official canon to the best of my knowledge.
Edit:
Forgot to mention, all Jedi are required to construct their very own lightsaber, and as such most handles are very different from each other.