I did P4Golden on the Vita.  I am undecided on the P3 version.  From what I understand some stuff was cut for the PSP version, but there were some welcomed updates as well?

Tales of 

At their best they are great stories with grounded themes like racism, idealism, meaning of life, ect. held together by strong cast of memorable and likeable characters and tons of interaction between them,  with catchy and energetic tunes and solid art direction with a fast paced and addictive real time battle system and enough depth in between.

Not every game is excellent, but they are still a fun time due to their battle system, every main title ranges from solid and good to excellent.

Tales of Symphonia is still my favorite RPG of all time, followed by other great titles in the series like Vesperia, Eternia, Abyss and Phantasia.

Overall Final Fantasy is my top choice, although they are not nearly as good as they used to be. Right now for me it's probably Dark Souls, but I'm starting to look more and more into Dragon Quest games.

Still Final Fantasy although I had problems with XIII and didn't enjoy XIV. There's too many gems for any other JPRG series to catch up.

Couldn’t have said it better myself. While the story quality might vary, the gameplay is consistently great and the characters are excellent. I love the optional skit scenes so much, it’s always a joy to see the characters interacting or enjoying the games’ quirky humor style.

Runner up would be the Megaten series. I’d say Xenoblade, but the franchise is really only 3 games, and while I loved the two I played, it’s still just two games.

Final Fantasy, although Persona has certainly made up ground with it's last few entries. Valkyria would likely be a contender, but we missed out on 3 and Revolution wasn't very good.

Right now it's Xenoblade

People also tend to be short-sighted when it comes to picking their favorite games. Breath of the Wild is the newest Zelda game, therefore, it's their favorite Zelda game of all time. This thought process tends to change as one gets older.

And if someone only ever played P5, and claimed it's their favorite series, then why haven't they gone to play any of the other games. Maybe it's just their favorite game.

Everyone is entitled to their own opinion, and I'm very open-minded and accepting towards all people. Besides, this is a completely hypothetical scenario. xD

I've only played Symphonia, Zestiria, and Berseria, and I loved all three of them. What I really love about these games is the combat. I haven't found a game that comes even close to the depth of their combat mechanics.

How are the PS2 entries?

Abyss is one of the best ones, is on both PS2 and 3DS.

Legendia is a solid entry, if a bit more basic.

There are also Destiny 2 and Rebirth but they are japan only games.