Borderlands 2 has a lot of replay potential without getting boring. It never plays the same way twice. The weapon drops are very different each time through. Don’t forget the DLC. The rest of the games in the series are fun too, but BL2 seems to be where it peaked for me.

+1 for Metal Arms Glitch in the System. It had some great characters and gameplay. It’s a shame that they never competed the sequel.