It's a toss between PS3 and PS4 for me. PS2 is a great console as well with a great library of games and even some of my all time favourite games like Ratchet & Clank 3, James Bond 007: Nightfire, Star Wars Battlefront I & II and Ace Combat 5: The Unsung War. I have a lot of fond memories of that console, but honestly I prefer both PS3 and PS4 overall.
Again it's a toss between those two, both consoles are great and also having a great selection of games. More so for PS3, but I feel that's a bit of an unfair comparison considering the PS4 library is still being built on.
The PS3 has so many great games, both exclusive and third party, that it's hard to pick just one game. If I'm going for exclusives, we have the Uncharted series, Killzone 2 and The Last of Us. Going by third party games, I would mainly pick both Elder Scrolls games Oblivion and Skyrim (especially Oblivion).
As for PS4, again the library is still being built upon and every year I find my personal favorites being changed. Right now I would say either Uncharted 4 or Horizon: Zero Dawn as far as exclusives go, and with third party games and overall I would say The Witcher 3: Wild Hunt.