Suikoden III, without question. Although, Suikoden I was just as magical. I don't understand the hype around Suikoden II; I just didn't enjoy that game at all. And Suikoden IV was ok, but a bit incomplete.

Havoc's Suikoden Series Ranking:

1 - Suikoden III
2 - Suikoden I
3 - Suikoden IV
4 - Suikoden II