Western RPGs easily, there are very few sadly, but when you get them, ho lee crap. I like Japanese RPGs & European RPGs too, but man, BioWare owns all. Only Blizzard is capable of putting out something with that same feel BioWare has, but they aren't in the single player RPG genre, sadly.
#3 Baldur's Gate
For over 10 years I never thought there would be a better RPG created. Set in the AD&D world of the Forgotten Realms, based on the AD&D Core Rules v2.0 This was table top gaming made right and brought to the PC for the first time in a way that actually not only made the video game version fun, but in a lot of ways, better than the table top.
#2 Dragon Age: Origins
12 years it took for someone to make a better RPG than Baldur's Gate and of course it was achieved by the same people that made the original. Dragon Age: Origins (named by the BioWare employees as the spiritual successor to Baldur's Gate) had mountains of possibilities both in role playing options and endgame results. Your choices REALLY mattered in this game, and because of it, you'd inevitably go back and play it at least one or two more times, or more until you felt you'd exhausted the different ways various scenes could play out and had discovered all the different storylines that lay down the path of one of the earlier branches in your journey. Mature, not XXX or needlessly gorey or anything like that, but Mature, as in grown up. Beyond that it was a great story to which neither movies, nor books could do justice. It's proof that video games are their own medium for artistic expression that nothing else can duplicate. It's not a video game, it's an interactive experience in a realistic fantasy world.
#1 Mass Effect 2
2 months after Dragon Age: Origins was released BioWare topped it with Mass Effect 2. This game really blurs the lines between RPG and tactical shooter, and yet, the best part of Dragon Age: Origins was streamlined here in Mass Effect 2; It's not a video game, it's an interactive experience in a realistic
fantasy world scratch that, Sci-Fi Galaxy. This is technically an RPG. You ARE Commander Sheppard, and the choices you make have direct consequence, moreover the choices you made in the first Mass Effect game alter what is available to you in this game, a feature that continues on to the trilogies finale. Commander Sheppard is a real badass, and you're the reason why. He's demented, he's sweet, he caring, he's heartless & cruel, he's funny, he's lame, whatever he or she turns out to be, it's on you. You are what makes Sheppard what he or she is.
From a personal standpoint, I can tell you that most of my life I've considered myself a theoretical fan of Sci-Fi. I am bored to tears of Star Wars & Star Trek, and without those, that the hell is there out there for Sci-Fi fans? Avatar? ... Anyways... I like Robert Heinlein's sci-fi. Starship Troopers, I liked the movie Pitch Black, I like Aliens & Predator, but compared to Star Wars & Star Trek, they're just a niche in the genre. Well... Mass Effect is MY Sci-Fi trilogy of choice, and I'm damned proud of it.
Mass Effect is sleek, fast paced, character driven, deep, mature, and completely awesome. It takes everything I like about Sci-Fi and lumps it all into one story, with everything that makes a good story as well. It's damned near the perfect game, no, correction, it's damned near the perfect interactive experience.