I collected for several years, been into emulation since the mid 90's, and am now starting to trim the fat on a morbidly obese collection. I hand pick CD based systems but as far as the older systems are concerned I find a Top List and add the specific titles I remember playing. The older or less popular the system, the smaller the Top List. So I might import 25 Atari 2600, 10-15 Colecovision or Intellivision, a handful of Apple II, Amiga, etc. Then I use no-intro sets for 8-bit on up where I spent a lot of time gaming, getting rid of duplicates and foreign titles where necessary. I played some titles when I went to Japan but other than that, gone. Some systems like the 3D0 are treasured to me because I wanted one but didn't have one. MAME has the worst calorie count and I am going to use Lord Monkus tools for dealing with that. I just see no point in collecting a ton of Colecovision and Intellivision arcade ports when you can have the real game in MAME, or 2,000 Apple II disk images when all you ever played was Oregon Trail and Zork in the school library. Of course, the full sets are backed up and I can draw from it as needed, but I want a more manageable and playable library.