i much prefer NV. everything is better, but the one main problem i have with FO3 is the lack of ironsight aiming. i just cant get fully immersed into the the whole role playing bit when my geezer decides his idea of aiming is to poke hs gun a little bit further forward and try to guess where he's shooting at NV obviously solves this.
also i dont like the concept of a sandbox rpg where your role playing consists of 'do nice things for the BoS because we told you too, and no, you cant go and be friends with the other equally armoured load of chaps (enclave) you also had no idea existed until you left the vault 5 minutes ago and who are seemingly broadcasting a message on the radio saying "were nice" because your not allowed, because we say so'