Devil Survivor>Persona 4>Nocturne>P3(P)>Strange Journey>Raidou 2>Digital Devil Saga>Persona 1
Out of the ones I've played. Imagine and Persona 3's The Answer campaign are not worth listing. I count The Answer as a separate game so as not to ruin my perception of Persona 3's main game.
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xfd dude, it's just a popularity contest on the internets.
-Vlado