Mass Effect Series for sure. Mass Effect 1's controls are a bit crude, and the inventory system is annoying. But 2 and 3 really nail it down. Playing through those will easily suck up 120 hours of your life (If you play the side quests and DLC's). But the story and characters are great. It my favorite game series ever.
I would also suggest The Witcher series. The Witcher 3 will be out this year, so good time to play through the first two. The Witcher 1 is a bit dated, but 2 is pretty polished and plays great. Well, minus the inventory system which annoyed me.