So what is the best game to start with?
I'd go with P3FES as well, but perhaps that's also because it was the first Persona title I started with.
The first SMT title I played was Digital Devil Saga, which is also very excellent but has a diff mood for sure.
P4 is great, but I still think I love P3 more for the characters and story, and I think it'd be an easier transition into 3 than it would be into 4 for a new SMT gamer.
Not trying to skew your view of the games or try to convince you to go for one or the other, but I do know that most of my friends have loved 3 and 4 but hated 1 and 2.
I had a hard time getting into 1 but was enjoying 2 on the PSP. It's definitely a different way of playing, but it's interesting to see how it evolved into P3. I gave in and purchased Eternal Punishment from eBay and was pretty annoyed because they shipped it in crappy packaging and the case got slightly cracked. Haven't played it yet, but all this talk makes me want to grab the CRT tv from my parents' house and play!