When it comes to D&D, and the WotC material in particular, I am highly selective. There are a lot of areas that just don't appeal to me (high level play, most adventures, many of the settings, etc.); I love the fresh blood provided by 3rd Party publishers, especially Malhavoc and Green Ronin, which tend to pique my interest more often.
There are some other games, though, where I am a near-completist and I do collect for a lot of different roleplaying lines (Ars Magica, NWoD, Paranoia, various Star Trek iterations, etc.), if that gets nearer to answering the question.