A friend and I are in the early stages of plotting out a game. I think it's going towards a Diablo style action RPG, but I'm reaching out to see what level up mechanics ya'll liked.

The information I'm interested is as follows:

What game was the system from:
What did you like about it:
What did you dislike about it:

While we are looking at an action RPG, I'm leaving this open to all kinds of level up systems (turn based, action, shooter, etc).