You know what? I agree with Tim Cain. Yes, Arcanum was ingeniously designed, it has a great roleplaying, but it wasn't really that enjoyable, because at places it got boring, and I had to gain a bunch of levels before I could kill that annoying "casual" Ore Elemental (or something) in that mountains Gilbert Bates sent me. I didn't actually got past that, I was too busy, but from what I've played I can say that. I also loved its character system.
Oblivion has a retarded leveling system and item leveling (if you do a quest at a high level, you receive the same ring you'd had received at lower level, but with higher stats). And if you somehow need that ring, but you've done the quest at a low level, then you have no way to get the high-stat version. This makes me think if they are intentionally being so retarded. Also, role playing is really stupid, Arcanum's is way better. And I hated the whole "you have to go to that place first before you can fast-travel to there" thing. Besides, there isn't much choice and consequences. And yet, I really enjoyed playing it (I haven't played the whole game, not even the half of it). When I ever find the time to reinstall it, I'll make so that I get maximum points per level, and if I do a quest at a low level, I'll use console to replace the item with the higher level variant when I get higher level. It's just so that this game is more grabbing, I can play it for a several hours straight without getting bored. I played it 2 years ago, but I think I remember it clearly.
Arcanum is way better in terms of role-playing elements, it has a better character system, it lacks some of the stupid flaws Oblivion has, it requires more thought to play, its idea is way better, but anyway Oblivion is more interesting to play. It's like a genious joke that you didn't laughed at, compared to an incredibly stupid joke that got you laughing.
Anyway, what applies to Oblivion applies to Fallout 3 too. Just for people who don't expect it to be the next Fallout game (like I did). Writing is terrible, combat too, well, there are some good ideas in the game, but mostly it's horrible. And yet, I had great fun playing it, when I visited every single location. I haven't tried the DLCs yet, but I can say that it's not a bad game. Just its RPG elements suck.