For kotor, I tend to use a soldier, Consular build... A soldier to get my dueling stats well than the counsular to build a strong force arsenal (I focus on using dark side powers, whether im light or dark side)... I tend to hace a high wisdom, charisma and dexterity rating, followed by strength and skills is each to his own
Kotor two, I tend to use a Gaurdian, jedi master build... same deal applies as kotor, I use the jedi gaurdian to do my feats up so I am a strong dualist, than I use jedi master/sith lord to strengthen up my force power arsenal (I like a mix in force powers with kotor 2, as some of the universal and light side powers are very useful to use)... Again, I tend to use a high strength, charisma and wisdom to strengthen my force powers and dueling again (This build tends to get everything you need by lvl 30, so you can do what you want after that)
I like using single saber for both characters...