As for me, I would have to say Fallout 3 is the best. The fourth installment is great as well, but they had tons of groundwork to build on, plus a much more advanced game system to play it on. For many, that would seal the deal. I mean, who doesn't love crisp graphics? (Not to mention ADS).

But Fallout 3 really started from the ground up, using lore from previous installments and running the Oblivion engine. What sets it apart is that they converted the classic 2D gameplay into an entire 3D world, and portrayed it lovingly with meticulously placed lore and little prizes at every corner of the map. I can't tell you how many hours I've played the game, and I still find new stuff.