I don't own any PSOne Classic games, but I've played the original versions of all of the games you've mentioned. My pick out of your list is Parasite Eve. It's a great real-time action-horror RPG with references to Resident Evil, Godzilla, and Clock Tower. You play as Aya Brea, a NYPD detective who visits the opera one night and gets sucked into a web of confusion as she watches everyone around her suddenly burst into flames. Over the course of the next few days, you're tasked with uncovering the truth and stopping the next evolution in genetics. There's an active combat system which requires careful consideration as you customize your equipment. Although there are some obscure rewards in the game, and the EXP is badly spaced between levels, the combat and story make it an overall enjoyable experience, in my opinion. The ending is also pretty great, what with its ambiguity over what really happens just before the credits roll.
Parasite Eve 2, on the other hand, is pretty shitty. The character models are chunky, and the plot isn't as great. It also has that awful turn-then-walk control scheme of Resident Evil and Onimusha, which makes the active battles where you have to run around and avoid being hit, or finding the ideal place to shoot from, a real pain in the ass.