Oblivion. Ugh. A household here of four PC gamers, all of whom had played Morrowind, some for years. Not a single one was playing Oblivion two months after getting it.
Oblivion ended my purchasing of Bethesda games at anything other than years-later-deep-discount. I wouldn't know aobut Fallout 3 except for someone buying it for me as a gift.
Personally, Morrowind was much more enjoyable, because it was foreign and exotic. For Oblivion they scraped all that off in their so-called 're-imagining'. Cyrodil ended up being a pretty bland place, pro forma fantasy fodder, not the Romanesque Empire at the center of previous legend. Repetitive, with a bland story (except for the Thieves/Assassain guild quests, which were interesting and had better design) and much overhyped over what it delivered. Bad voice acting, AI, and leveling concepts. 'Have you heard about the Mudcrabs??'X1000.
They built up a lot of press because of the graphics. Most reviewers had only a couple of hours in game, not nearly enough to work out what the problems were, before they wrote their glowing reviews.
While it might be transformed radically by modding, I just haven't had the interest to go back there. Fatally flawed in my estimation.
Oddly, I liked Fallout 3 way more than I thought I would. Better story bits, better voice work, if only it wasn't buggy as the day is long. And didn't use Windoze Live stupidity. I have only recently gotten to where it doesn't crash every hour or two. I will say, having played 'The Pitt' on a friends machine, and I was impressed with it. It gave you some diffcult choices. They were tough for me, not the usual easy or simple ones.