Get both, but if you have to get one, get R:TW for now. It will at least give you a new time frame to play around in since you've had M:TW all this time and make sure you get the mods for it(EB, RTR, BL, NTW2, etc.), and then later on if you want get MII:TW then by all means, and by then the great modders here at TWC and elsewhere should have some fantastic mods released for it.