I found Portal just recently even though it was released in 2007. I picked it up because I thought the title was interesting.
I was a bit suprised to advance through the test chambers, waiting for the enemies to pop up and the game to actually start. And then it was suddenly over. At first I was a bit annoyed by the jokes.. for example the cake thing too overused to be funny (I actually didn't realize it was Portal that started it). But I did get into it eventually and actually enjoyed the game (and GLaDOS' o' so cynical monologue).
Anyway, even though our relationship started slightly clumsily I ended up playing the sequel shortly after. I knew what to expect this time but damn, Portal 2 felt much more like a real game. The characters got more depth and I liked the trip to the past of the facility. I think the game triggered a bit of a Stockholm syndrome and by the end of the game I hoped the mute lunatic would stay in Aperture laboratories with the homicidal AI. My poor ex-girl had to listen to me babble about the game too much. She eventually agreed to play the co-op with me so it wasn't all in vain.
I rarely play favourites but it'd be easy to pick my favourite game antagonist. Perhaps even the protagonist.
PS. the turret is "different".