I would have voted for Fallout all the way, I've been hooked since the first one. The Fallout series has one of the best re-play values, in my opinion, not to mention the amazing character interplay (excluding Fallout:Tactics of course) and gritty, engaging format. I enjoyed the Elder Scrolls series, but never really felt worried about my characters survival or ability to actually overcome the final challenges. The "skin of your teeth" feel in Fallout really helped get me into the game. I am somewhat inclined towards post-apocalyptic scenarios in general though, my favorite movies growing up being titles like "A boy and his dog" (a direct influence on Fallout) and the Mad Max series.
