Well...when Morrowind came out, I had never played an RPG (I'm not exactly new to gaming...18 years of it and counting), but no RPG really ever caught my eye before (Unless you count the Diablo series...which I don't). Morrowind looked great to me, so I *cough* pirated it *cough*. I liked it enough to buy it, and yet I never finished it. (Disclaimer: I haven't pirated a single game since 2003, and I've ended up buying every game I've pirated since Morrowind except for Halo PC.)
Oblivion wasn't such a success for me. I thought it was incredibly bad design to start you out in a dungeon with similar looking everything, and nothing of interest at all aside from a certain Star Trek captain biting the dust, but even that you knew was coming. By the time I stepped outside, and had to find my way to somewhere, I was done. I haven't felt a single urge to play the game since.
Despite my bad track record with Bethesda games, every single feature, trailer and screenshot of Fallout 3 made me want to play it. Now, I haven't finished it yet, but that's more because of my methodical and slow play style. I've put over 80 hours into it, and yet, I still keep going back.
My vote is obvious.
EDIT: I never played Daggerfall, but if this quote by Ken Rolston is any indication, I'm glad. "It's amazing anyone could play it at all, the shape it was in when we shipped it"