Predominantly I'm a dual wielder.
Sometimes I double blade, others I single wield (classic look and in TSL it has the thrust/stab motion that way). Really I do them all. Cuz it's fun.
In KOTOR I tend to prefer blue and either green or violet. Until I get near end game, then I use MotF (turquoise) and HotG (red-orange with yellow core).
TSL I use whatever I can get until I can get the silver crystal or the orange crystal.
Power crystals? Well that's the thing. I usually have multiple sabers. One or two for dealing droid damage, at least one for deflection of blaster fire, one or two for pure brute damage.