Huh, that's interesting. I'd go totally different:
1: Fallout 1
2: Fallout: New Vegas
3: Fallout 2
4: Fallout 3
Fallout 1 is the "purest" of the games, I think. Parts of it haven't aged well, but 2 has that problem also, and 1 doesn't have the weird jarring excess of "humor" (note the scare quotes) that 2 does.
I rank 3 so…