Mirson on 02 March 2010
Persona 3 & Persona 4 aren't story related to each other and the earlier ones, so you can play whichever one you want first. I recommend you wait for Persona 3 Portable - it's coming out this summer.
Devil Summoner 1 & 2 also aren't story related. Though I recommend you don't play Devil Summoner 1 - it kind of sucks.
SMT: Nocturne is part of the main series (the others like DS, Persona, etc, are spin-offs). This is my favorite SMT game. I would like to recommend this game as the place to start with SMT since it does a fine job introducing the demons and what SMT is all about, but be warned, it's a pretty difficult game.
Digital Devil Saga 1 & 2 are the only ones that are story related.
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