For PC, you can use either version. If you do not have an Xbox, I suggest going for the Playstation version for the cost save.
As for differences:
Mobius: Mobius is designed primarily for the needs of the high-end advanced PC gamer who wants 5.1/7.1 surround sound, head-tracking, and keyboard macros. However, if you want a wireless headset, the Maxwell is your answer.
Penrose: Maxwell is our next generation gaming headset. It improves on Penrose in most aspects, as well as including the addition of USB wired audio, which Penrose does not have. I recommend you check on the Maxwell page for specifics. There's much more as well.
LCD-GX: this is still our high end, analog gaming headphone/headset, which is traditional in which it is wired, and works with anything with a headphone jack. It is also open backed which leads to a more open sound. This is for serious audiophiles that want the ultimate in audio quality first.