3 years ago I played all the Fallouts for the first time, in order. It was awesome, and one of my best gaming memories ever, although I did end up rushing through FO3 just to finish it for completion's sake.
I prefer FO1's compact storyline. It was the shortest of all 4 games for me, but I kind of liked the immediacy of having a ticking clock over my head for most of the game. It made me feel like the game represented a living and breathing world that would go on without me, rather than pausing while I do a bunch of side quests (although, I realize that you can buy extra time at certain points).
That said, FO2 and NV are great sprawling, companion focused, RPGs. I think both are equal in terms of storyline and companions (I actually think I prefered NV's companions overall, which might be blasphemy). NV does have Gamebryo combat, which is a definite impediment, but honestly FO1 and 2's turn based combat isn't exactly super complex either. The main virtue of those games' combat is that it can usually be avoided, where as its harder to avaoid combat in NV.
FO3 sucks in all respects, except art design and level design. In terms of art design, I do give them credit for translating the look of Fallout to a 3D setting. As much as I hate the game, I do think the look of the the interiors of the Vaults, for example, were dead on. And most of the rest of the world looked great too, capturing the general "future by way of 1950s instructional videos" aesthetic of the earlier Fallout games. Likewise, I think the basic landscape/architecture and level design of the game is great (barring some of the tedious underground tunnel sections). As much as I liked NV, for example, most of its level design tends toward the flat and functional. There weren't any cities as interesting as the multilevel Megaton, to name one FO3 example.
But while the world looks great, it's boring and doesn't have any of Fallout's flare or character. Megaton is another great example. It's like Bethesda decided that the tone of the older fallout games was "wacky" so they populated the town with a bunch of broad, wacky, sub-sitcom level characters, like that chick who makes you create a cookbook for her. Which I think is a massive misreading of tone and central conceit of the original Fallouts. The original Fallouts had some comedic elements, but they were always less broad in their comedy and much more satirical. Their comedy usually came at the expense of very specific targets and ideas, and most importantly, they were usually grounded in very realistic and very serious characters and situations, which often cast the comedic elements in sharp (and sometimes disturbing) relief.
I love playing Fallout 2 as a naive evil doer, for example. A gullible hick who does terrible things, not because he is deliberately bad, but because he just doesn't know enough about the world to not be influenced by the bad intentions of others (a play style which can be mined for lots of humor). That sort of contrast between horribleness and wide eyed, "gee-whiz," 1950s naivete is the central contrast which gives the entire series its creative spark and vitality (one needs look no further than some of the perk artwork to see it, afterall, much of which shows the smiling, cartoon, Vault Boy doing horrible, horrible, things).
