For me Fallout 3 = Oblivion with mods.
Fallout 3 is just so much more "finished", Bethesda really learned from their mistakes with Oblivion and make a game that is actualy good in it's vanilla form.
Oblivion lacks that, with mods it can be made perfect but it's very sketchy otherwise, leveling and progression to name a few have issues that just ruin it for me.
So basicaly, if you are on a console Fallout 3 is what you want, if you are on a PC....well for me it's still Fallout 3 but Oblivion can be made just as good with a few select mods if you prefer medival to future/post-apocolypse.
Fallout 3 is just so much more "finished", Bethesda really learned from their mistakes with Oblivion and make a game that is actualy good in it's vanilla form.
Oblivion lacks that, with mods it can be made perfect but it's very sketchy otherwise, leveling and progression to name a few have issues that just ruin it for me.
So basicaly, if you are on a console Fallout 3 is what you want, if you are on a PC....well for me it's still Fallout 3 but Oblivion can be made just as good with a few select mods if you prefer medival to future/post-apocolypse.
I preferred the atmosphere in fallout 3 aswell.