fallout new vegas is on top for sure, that game easily bumps up every single good thing FO3 did and more, it actually had a story (dont give me that crap, the FO3 main storyline was a piece of trash, liam neeson is the only thing that saved it. liberty prime was his protege)
the amount of content and fun in that game is gonna have me satisfied for years.
next would be oblivion (hopefully skyrim ousts this and new vegas, im pumpeeddd to see the upcoming videos for that), i love the fantasy setting, and oblivion delivers that with an awesome open world, yet fun filled adventure. the main storyline is pretty crap, but the factions and sidequests actually make up for it, along with the world not looking like a fucking steamrolled turd like fo3 does, so with magic, swords/shields, and bow + arrow, its alot of fun and its endless on what you can do.
so in short
fallout new vegas
oblivion
snacks
toilet paper
fallout 3