1, definitely- it's a better starting point both chronologically and difficulty-wise; those games have a pretty steep learning curve, and 2 is just huge and complex compared to 1. But that's my somewhat biased personal opinion, since Fallout 1 is one of my fav games ever...
Oh, and whoever voted that they both suck must either:
A. Be really ignorant
B. Be too dumb/lazy to play a classic CRPG (Lets face it, those games were both more difficult story- and combat-wise by miles)
C. Have a legitimate excuse such as Fallen-Angel, in which case i completely understand.
Sorry for being a bit of an elitist troll wanker
Peace.