in Dragon Age, my favourite party is
1: Me, as a mage, blood mage/arcane warrior.
2: Sten, 2 hander berskerer specialism. I love Sten, because his sarcasm is delicious

3: Zevran, assassin/dualist specialism. Because any guy that can come on to me as I'm trying to kill him is grade A awesome.
4: Shale, because I need a tank who hates pigeons, really. That and she's generally funny.
In ME1, I take Wrex and Tali, because I'm quite fond of both of them, and their talents work well together.
In ME2 I take Garrus and Tali, because Garrus is totally awesome.
In KOTOR, HK-47 and Bastilla - because, well, HK-47 is hilarious, and I actually like Bastilla as a concept and character. She's in an impossible situation and does her best to work it.
In KOTOR 2, HK-47 and Kreia, because they're by far the best characters, Kreia being one of the best characters in RPGs full stop. I usually take Atton before I get HK, because he's one of the few 'Carths' (vanilla lightside man who accompanies you) who isn't made of suck. Alistair being the other exception.