1. Dragon Age: Origins - An immersive game at its best. It has a great plot, great characters, and a great world. When you take the game apart and look at each part of it individually, the graphics, the gameplay, the controls, it doesn't look all that spectacular, but when you mix them all together, it makes something incredibly good, the likes of which I've never seen before. Simply fantastic.
2. Fable: The Lost Chapters - One of my first RPGs, and the reason I got into RPGs. I never heard any of the hype before playing this game, and from a blank slate, it simply amazing. It's immersive, your character dynamically changes for their alignment, the story is great, it has one of the best villains of all time, and it's simply an amazing game in general.
3. Fallout 3 - I didn't know what to expect doing into this, but I love this game to death. It has a huge immersive world with each location being relevant in its own way and having story behind it to find, the voice acting is great, the combat is fun, leveling is fun, and the whole game was polished to a mirror like shine. I dumped over 200 hours into this game, and I can't wait to do the same with New Vegas.
Honorable Mention. Paper Mario: The Thousand Year Door - I have a soft spot in my heart for the Mario RPGs. I love the Mario and Luigi series despite the small hiccup at Partners in Time, what I've played of Super Mario RPG is great, and I simply love the Paper Mario series (Except for Super Paper Mario). This game is able to keep everything fresh with the funny dialoge, the dynamic fighting system that has the crowd throwing items at you, the backdrop collapsing, and the enemies doing cool things in battle like attacking the crowd. This is simply a fun, fun, FUN game.