Since playing FNV, I've decided that my favourite genre of game is FPSRPG (First Person Shooter Role Playing Game). I love the elements of this that combine the combat-heavy nature of a dedicated shooter (such as Call of Duty, Halo or Battlefield) and something with a thick adventure-based storyline that gives you the freedom to make your own choices. In turn, this affects how things turn out for you later, if you end up 'good' or 'bad'. I think New Vegas handles the two smashed together pretty well.
With that in mind, are there any games you can recommend that are like this one? I'd love to have a proper sandbox world that I can explore and run around in (and play at my own pace) with an added emphasis on combat, and from a first-person perspective only. I had a go at Farcry, but was disappointed in many ways. Fallout 3 for me was horrible.
Sorry to have been vague in what I'm looking for, but does anyone have some ideas? I'm on the 360.