GTAs mentioned above do have freedom, true, but are pseudo-linear. You cannot choose different paths to progress the story, unless it is 2 that we are talking about (GTA 2), in which you choose which gang you are going to work for... And as far as i know, every GTA game, has only one ending, each. I would say GTAs are not the type of game OP wanted.
I would double the Vampire:Bloodlines, which has to be EXACTLY that. Many different endings, many ways to finish even ONE quest (out of the many), different approach to conversation and combat (even avoiding combat altogether), etc.
Witcher also fits, but 1 more that the others, since it has neutral ending, many more choices reflected during the epilogue act and unlike 2 and 3, it doesn't downplay, or downright CANCEL, your OWN, damn choices. Plus it allows you much more freedom concerning how many types of women you can bed, throughout the game; more even than in 3...
Baldur's Gate is nice, but hard, a hardcore RPG but rewarding and satisfying. Different endings are not that many, actually, but you can ropleplay a good, evil, or neutral party. You have to carry and stomach a party, though.
Post edited October 16, 2015 by KiNgBrAdLeY7