New Vegas is a better game. And I mean that in the sense that you can go more places and interact with the story and setting in more ways in New Vegas. Also, what do they eat? Fallout 3? unknown. New Vegas? you see corn fields and such all over the place.
In Fallout 3, the NPCs have no existence beyond their part in the highly scripted story. You choices in game don't matter at all in the way the story ends.
New Vegas has little bits and pieces of setting and backstory for random NPCs that you might never meet, and the story can be completed in different ways, your choices matter.
Shattered Pixel Dungeon is a damn good game, and highly addictive. It's on the older side, but is still actively developed. It's available basically everywhere.