Guess I'll explain how I personally felt about each library.
PS1: 3D gaming had just begun so pretty much everything was mind blowing. Voice acting, orchestra music, and CGI cutscenes just felt like the future had arrived. The PS1 was where 3rd parties went insane with innovations. Game prices ranging from $9 to $40 (compared to the competition's $50-$80+ games) meant I easily topped 100 PS1 games.
PS2: After the slow first year, the library guy kicked into overdrive and never looked back. Games looked better than ever and several key franchises were born. A PS2 was really all you needed.
PS3: Same as PS2 but this time, Sony finally started created many of the best games on their own system. 3rd party support was still strong but developers took less risks due to rising production costs. The first generation where I didn't think the PlayStation brand offered the best overall experience on the market. Still an A+ offering, though.
PS4: Sony still pushed gaming as hard as it could go but a lot of the "wow" factor just wasn't there for me. A lot of games I wanted to love just fell flat. Side effect of me getting old, I guess.
PSP: Couldn't believe I was playing some of these games in the palm of my hand. Lots of franchises I'd never even considered became part of my library (wtf is a Gurumin!?) and I loved them. Felt like a kid again. Great first and 3rd party support.
PSV: Despite a lot of good times, it just felt like Sony wasn't trying. They kinda left this one out to die. Found myself buying certain games, not because I wanted to but because there was just nothing better to choose from. After the first year, my Memory Card was full. I bought what I could physically (lots of stores didn't carry Vita games making it even tougher) and certain games like FFX required download space that I just didn't have.
