Personally the N64 is the newest system I plan on collecting for. There are two reasons for this: One is that I only want to collect cart based systems as the games themselves have a very long lifespan. Where as cd's eventually get scratched or deveolp disc rot which is a real turn off for me. On top of that when buying disc games used there is a much higher chance that they are damaged.
Second is that many games made after that just don't appeal to me. I mean some do like zelda titles. But looking specifically at the Wii (I only collect nintendo at the moment) for every good game there is a good 20 that suck. I work at a Toys R Us and there is about 3 games we have now that I would try on a shelf of about 100 it is really sad.
Third (yea I know I said I had two reasons) is that the librarys for systems put out after the N64 are huge. I just looked up the list of Ps2 games on wikipedia and its over 2000 games long. Granted some are region exclusive but still that is alot.
So which generation of game consoles do you plan to stop at and why?