My vote went to Portal. One of the most fun puzzle games I ever played and different then any puzzle game I played before it. Had a lot of fun playing through it.
Second place for me would go to Mass Effect. My favorite of the 3 mass effect by far. Starting with mass effect 2 I felt it went a little to much toward fps combat mechanics vs RPG elements while the first one maintain more of the KOTOR mechanics I liked. I did not play mass effect until it released on PC.
Favorite game release in 2007 was Witcher. I loved the story, number of side quests, the environment and world building, the graphics might of been dated but they was perfectly fine with me. Even the old Never winter night engine it used was fine with me. The one thing that holds this game back for me and the only reason I put it behind mass effect is I HATE the battle system. The entire click wait x second click wait x second click might be the most hated combat mechanic I ever experience playing a RPG. For someone that never played it guess best explanation is combat work like a rhythm game but it just not fun (to me) in how it implemented as the combat system.. Since combat a big part of the game it prevent this game from being higher on my list of favorite RPG.