Fallout: Brotherhood of Steel!
(JK)
But all seriousness, for me personally it's between either Fallout 1 or New Vegas.
For Fallout 1, it's because like what everybody else has been saying in this thread: the setting, tone, atmosphere, the storyline ETC. basically all the things that perfectly capture the Post-Apocalyptic vision that The Development Team had for it, plus the "Hero's Journey" as everyone else has mentioned.
Now as for New Vegas yes, I know this answer is an obvious one, but other than giving the usual reasons as to why it's SO good. Here's something that I think, makes New Vegas a great entry in the series...
FINALITY!
Basically if you treat it as a conclusion to the story arcs of the factions/characters that started in Fallout 1 & 2, you'd get a game filled with rich lore & world building, with endings to their arcs that are up for you to decide:
The (Great) Khans: Given a chance at redemption & glory, OR wiped out ONCE AGAIN!
The Enclave Remnants: Go out with one last hurrah! OR pass away peacefully or at worst MURDERED, taking the secret of their dark pasts to their graves.
The West Coast/OG Brotherhood of Steel:
Begins to cooperate with those outside of their own walls/organization, OR regresses into being even MORE isolated & xenophobic, which essentially turns them into glorified Hi-Tech Raiders.
The Master's Army Remnants:
Living the peaceful normal lives that they've strived for so long,(well, at least those who seek peace) OR die the death as the perceived monsters that's been hanging over their heads since The Fall of The Master.
The NCR: Continues to grow as a organization by getting a 3-PEAT W! Conquering more territory in the Mojave, OR gets knocked down a peg, retreating back to Cali from the Mojave by either Mr. House, The Legion, or That Crazy Ass Mailman!
So yeah, those are some of the examples that I could think of at the top of my head, let me know if I missed anything.
