As far as my opinion on Fallout 3 versus New Vegas, I'm pretty much in the same boat as Regulith.
I just enjoyed Fallout 3 more. I found the location of the game to be more preferable.
I'll accept that it's probably not a great Fallout game, but then I never played Fallout 1/2, so I didn't really care.
Ultimately, I enjoyed exploring that broken down city/country side, fighting weird creatures, using lasers and garden gnomes for weapons, and having Liam Neeson as my dad.
As far as what I hope for out of Bethesda's E3 reveal, I would quite like either (or both) a Fallout 4, or an Elder Scrolls VI.
I think it would really really ruffle feathers up for Fallout fans (traditional fans), but I would love it if it were changed up drastically, and we had a Fallout that takes place not in America, but perhaps, China, or maybe Europe.
It'd be nice to see how the world differs on the other side of that conflict.
Of course, you'd probably have issues with things like including key ingredients of the games, such as Vault-Tec, Vaults, Vault Boy and Pip-Boy.
Perhaps there could be an equivalent Chinese version, or maybe a subsidiary company doing similar work in Europe.
Eitherway, I would enjoy seeing that. Get a completely new spin on it, where at least for the most part, you have less of a chance of Fallout1/2/3/NV fans moaning if you don't include something, or include something that shouldn't be there.
For Elder Scrolls VI however, I think I would very much like to see Black Marsh and Elsweyr, maybe Valenwood. They're three hardly explored regions in the core TES games (not including TESO), and from all the descriptions of them, they are some of the most vibrant locales in the series. They have marshes, bogs, islets, dry plains, forests, jungles, beaches, wandering tree cities, etc...
Furthermore, you get a real look at some new cultures/politics. Elsweyr I believe is part of the Aldmeri Dominion as of the 4th Era and following the Void Nights, which really affected the Khajiit people, and Black Marsh is now independent, having retreated from the Empire and following on from their invasion (and then retreat) of Morrowind.
We'd really get a chance to see new cultures that aren't so heavily influenced by the Empire.