This topic is locked from further discussion.
Mass Effect 2 wins this easily for me.
I mean come on - Mordin? Thane? Legion? Nothing in skyrim formed an emotional connection with me as strongly as a single one of those characters - let alone when you start adding guys like Grunt and Garrus/Archangel.
Tough call. Spent a lot more time with Skyrim, but that doesn't necessarily suggest a preference.
I can buy the argument that ME 2 didn't have the heart of the first game, but one could easily suggest the same about the relationship between the first two Assassin's Creed games as well. In both cases, the first game had an imaginative if incomplete vision that was kind of all over the place quality-wise and the sequel doubled-down on what it wanted the series to be by keeping what worked and eschewing what didn't. In Skyrim's case, it was the closest those of us who have been with the series since Arena have to a fully realised Elder Scrolls game. It's a bit tragic that we have to wait five years each time to see an incrementally improved version of the same idea, but Skyrim's a culmination of a really long journey. Then again, episode six will probably be even better (Bethesda could learn a lot from studying Dark Souls's combat, for one thing), so...
I voted for ME 2, but it was more or less a coin flip.
I'm fine with either, really, though I still put far more time into Oblivion than I did Skyrim and I personally think it should've been on this list instead.
Skyrim had such a better combat system that any inclusion of oblivion, no matter how cool certain quests were (I'm certainly not saying the Skyrim quests were that great), would've been... odd.
ME2 was a special game for me because it was one of those rare games that lives in a certain point in my life that will always make it memorable. I guess it's just nostalgia, but I feel like that implies more time has to have passed. Funnily enough, Oblivion is another one of those game, and I might've chosen it had it been the choice.