PSX. A lot of revolutionary stuff happened there and it was awesome. There’s a lot of fun in collecting variety to be had there too. Black label, greatests hits, boxed sets, lightspan, long box, not to mention have you guys seen that Japanese square millennium collection stuff?
https://finalfantasy.fandom.com/wiki/Square_Millennium_Collection
I gave up on dreaming of the PS1 full set years ago though.
Although, I almost exclusively collect NES now with the occasional long box thrown in.