Probably the PS1, while the PS2 is a great system in its own right, I felt it was pretty slow to start and certain companies really missed their mark while others finally rise from the shadows.

As a fan of JRPGs though, the PS1 has the better pedigree and it was a more exciting time to be a gamer whereas I feel that the PS2 is when several developers finally went into business mode, so PS1 just felt like a more creative time for the designers and the fans. It's also the middle and end of Square's Golden Age, they never quite bounced back to their "do no wrong" era of PS1 as most of Square's titles in the PS1 era are pretty enjoyable on some level whereas it always felt more hit and miss in the PS2 era before striking out in the PS3. Capcom also never quite held my interest after this era. It's hard to beat SFAlpha 3, Breath of Fire III and IV, and the MMX series really hitting its prime. Also Symphony of the Night and the birth of Rhythm games.

On the other hand, while I love me some Persona 2, I feel it's hard to argue that MegaTen as a franchise came into its own on the PS2. SMTIII, Avatar Turner, Raidou Kuzunoha, and Persona 3 and 4 are easily some of the best games to come out of the company in years and while they are still going strong, it's hard to find a lineup past the PS2 era that is equal in terms of overall quality and mass appeal. Konami also had their last hurrah in this era, with MGS 2 and 3, Silent Hill 2 and 4, and some killer DDR titles.

So its a toss up between these two but the nostalgia-tard that I am will probably say the PS1 because it was the last time I ever felt really excited to be a gamer.