Rage is the most comparable with the Fallout series, with a little less customization. It also includes vehicles and, in most areas, a more apocalyptic feel. In, my opinion, better than fallout New Vegas.
Yes, it is a zombie game, but not a simple survival game. It is more RPG style with an open world and LOTS of customized weapons. You receive missions for XP and upgrades. The trailer sums up gameplay pretty well.