I couldn't bring myself to finish Oblivion for the longest time and just recently I finished it. I got all 60 achievements and finished the DLC, so there is officially no reason for me to ever play that game again.
Of games I own, I also really can't bring myself to finish Final Fantasy XIII. The combat is so... well, let me put it like this:
Fallout 3 mixed Real Time and Turn Based combat quite well by clearly separating them (When you're in VATS, it's Turn Based, if you're not, you're in real time), but FF13 tries (and fails) to mix them together. It makes for awkward combat, although the Pardimes were pretty cool.
Also, the game is almost criminally linear for an RPG series that's supposed to be so much about the open world (at least from what I've heard of everyone else).
And really, why did you quit Mass Effect because of the monkey quest? It's just a side quest, so if you really hated it THAT much, just skip it. There's no reason to do such an unimportant quest if you don't want to, and one mission isn't much of a reason to hate a game.