While many will argue that Final Fantasy is the best RPG series, I feel that Suikoden rightfully deserves this honor. The stories in Suikoden generally have more realistic stories than Final Fantasy, usually involving a conflict between two countries or a civil war. On top of this, instead of taking on the role of some nobody, every game, with the exception of the second one (and arguments can be made in that case) you take on the role of somebody who you would expect to be a leader, be it the son of a country's best general or a prince. And instead of the game revolving around a group of 8 or so people who are supposed to save the world on their own, you can recruit up to 108 party members, along with having your own army, so it is a lot more realistic in that department.
Unlike Final Fantasy games, every Suikoden game takes place on the same world. This allows for some continuation between games, but not enough to be considered a direct sequel. Each game has its own plot and location, but these small links show a greater story that spans every game. On top of each game being quite fun, this factor gives you more incentive to play each game.
The gameplay is rather easy to get a hold of, which is a good thing since the game has no tutorial, unlike Final Fantasy games, which teach you how to play over the first hour or so. Until the latest installment, battles were pretty straightforward with you having a party of 6 divided into 2 rows, Now, however, different formations have been added that give different benefits when you use them. In my opinion it also has one of the better magic systems. Each character has a total of 3 slots (although some characters don't get access to all of them) to install runes. Some runes bestow the character with benefits in battle, and others provide magic spells. Each magic rune has 4 spells and depending on your magic stat decides how may times you can use each spell before resting.
After all of this, I feel that it has one of the best villains, even surpassing Sephiroth and Kefka. He appears in the second one as the main antagonist and is named Luca Blight. On top of being even more psychotic than Kefka he also has the best death scene, except for maybe Aerith's. So, if anyone is still reading this I highly suggest you try this series, but make sure you start with the first one. I guess it probably would have been easier to just post this link, but whatever.
http://www.suikosource.com