Suikoden II and V remain my favorites. Suikoden IV was good in my opinion, the graphics were nice, the battle interface was good, only sad that only 4 characters could enter. But I also thought it was lacking a real "world"...just a few islands, a few of which are only meant for treasure hunting. The boat travels took far too long sometimes, with all the random battles around. I have nothing against random battles on the worldmap, but I do when it takes about 10 minutes to get to another island even without fights.
And I thought it was far too easy to miss a lot of events. First time around I went to Kika's island when it first became available. As such, bad items, barely any characters... Second time around it rocked, though...especially when I got Mitsuba early in the game. I

Mitsuba.