My vote goes to 3. Any version is probably alright for different reasons but I played Reload. The PS2 version has the most consistently good-looking art, though.
I had tried 2, 4 and 5 before but couldn't get into them a lot. Tried P3R on gamepass on a whim and I was completely hooked. The presentation was way more interesting to me, and as someone who doesn't even particularly like juvenile edgy weebshit (which is what I gleaned from the whole series at a surface level) I think it struck a really good balance between being both 2edgy4u and earnestly beautiful at the same time.
Its story is pretty malleable and also seems to be pretty colored depending on what kind of disposition you have as a player. Some people feel it's really depressing and overly gloomy, while others (me included) see it as more of a hope/perseverance kinda deal. Both are valid and you can apply both mindsets to the player character through dialogue choices.
Also made 28-year-old me nostalgic for the mid-late 00s which was enjoyable.