I've always wanted to try the series but was never sure where to start.
Suikoden I
It's still a great game; takes only 20 hours to beat, maybe 25+ if you try to get all 108 stars of destiny on your first play through w/o a guide (good luck w/ that :) ); the story in Suikoden II is pretty much a direct sequel in the bordering lands w/ tons of returning characters; and if you have an end game Suikoden I save file to load when you start Suikoden II, you get a very nice bonus...