Truly one of the greatest RPGs ever created.
I'm constantly in awe at the degree of care that went into the world-building, there's not a single bit of lore discovered in this game that doesn't tie itself back into the motivations of the many different characters across the many factions in the Mojave.

While I understand how many people would prefer the gameplay of FO4 (sans the RPG mechanics), I still find the moment to moment action of NV far more enjoyable. Greater diversity of weapons, ballistics feel punchier, the gore is just satisfying as its ever been, no superfluous junk mechanics, etc. It's all the meat and potatoes of what makes this game sit well in your hands with none of the junk food that FO4 would add on top of it later.