PSI - Once (I just started playing it yesterday on the Ultimate collection actually)
PSII - Once (Barely scratched this game)
PSIII - Twice (I had to restart because I ended up saving in the middle of a dungeon and kept dying)
PSIV - Eight or nine times I think, I love this game.
PS Gaiden - Once, never beat it but it was alright
PS Adventure - Once, but I couldn't get into it
PSO - Three times. It was alright just not as good as I thought it could be
PSU - Once (I would have kept playing too if my PS2 didn't break. Stupid newer model PS3 won't play PS2 games either

)