I've never heard of Sacred 2 until now, however, Oblivion is pretty damn awesome. People say it's not as good as Morrowind, but I haven't played that so I can't comment. As for Fallout 3, I bought it the other day but haven't got round to installing it yet, I got F3 on PC but Oblivion on Xbox 360. Basically, it's up to you, but in Fallout 3 I've heard nothing but good things (apart from the ending...). However, apart from financial restrictions, is there any reason why you can't get more than one of those?