Fallout 3 or Borderlands (pc)?

I prefer Fallout 3 because there's so much to do and if you like exploring in games then this is the one for you. There's fun achievements to try and do, but i'm not sure if you get to do them on pc. There is lots of easter eggs to find too, such as a crashed alien spaceship and jesus! As well as all of this for about �10-15 for 3 add-ons on one CD. There are six add-ons altogether which makes the game even bigger.