I like Fallout 3, I honestly do, despite the very annoying mishaps in it, but it's certainly not on my top 10 games of all time or anything along those lines. It's a good game, and the modding community will, just like Oblivion, add to it, tremendously. And Game of the Year... I don't know, I'm not sure, I really liked Clear Sky, also despite the very annoying bugs and whatnots. I also liked Red Alert 3 and FarCry 2.
In my book it'd be a tie between Clear Sky and Fallout 3, but Fallout 3 is more recent, and it needs mods, badly, while Clear Sky was alright without mods, it's just buggy, but if it was functional, if the Faction Wars would work as it should (and as it can, but modding will do it, not GSC) then I must admit that I'd be spending more time on Clear Sky at the moment. But in the end really, they're all nice games, I like them all, I don't plan on asking a refund for any of them, and I will keep playing them in the coming months, but... yeah, Fallout 3, GOTY or top 10 games of all time? Nah, not for me.