I've played KOTOR/KOTOR2/a Nintendo 64 game but I can't remember what it was called, and I played The Old Republic.
To be quite honest, I have more fond memories playing SWTOR than I have any of the others. Me and a friend played through it (sith side) together, I was an Imperial Agent and he was.. the magic user, can't remember the name of that class. Anywho, we basically went through the whole game together and did every single story mission together so we could check out both stories, it was really fun. The game got boring fast at 50, but the path there was a blast.
KOTOR comes in second, was a really good RPG but I'm not a huge Star Wars fan, so all the lore and story and stuff wasn't super appealing to me, so mostly what I got out of it was just the RPG elements, which were great at the time... but I enjoyed SWTOR better in all aspects, and playing the whole game with a friend was a big bonus.
"You lack the requisite spine and testicular fortitude to study under me"