Suikoden II is the best game ever made, in my opinion. Amazing story, excellent characters, entertaining gameplay, plenty of side stuff to do (I love the ever-amusing cooking sidequest) -- it's just all-around a very well made game. Suikoden specializes in mature, intricate plots and II especially did a really good job. Jowy is arguably one of the best developed video game characters, and Luca Blight is definitely a great villain.
A thousand thousand times this. Jowy is my favorite character in a video game ever and everyone should share this opinion. Suikoden II is amazing.

As far as I know, Suikoden VI hasn't been confirmed. The last I heard, Murayama was accepting offers from a SUPER MYSTERIOUS COMPANY (Konami) but that was in late January. It has been fairly quiet over on SuikoSource though, admittedly, I spent less and less time over there.

Suikoden I was a good game, a great introduction to a wonderful series. It is not, however, one of the greatest games ever made. It does the job of a first entry into a series very well though.

Suikoden III is hit-or-miss in my eyes. When I first played it, I disliked it for the sheer fact that it was far different than the previous two installments. As I continued to play the game, I enjoyed it more and more. Now I appreciate the differences enough to enjoy it thoroughly.

I am in the minority of those who enjoyed Suikoden IV. It was not the best game (indeed, it is perhaps the worst of the main series) but it was not a bad game by any means. The storyline was decent, the characters were developed in some of the correct places and the setting was amazing. There were some things they could have done different, sure enough, but as it stands it was a pretty good game itself. Barring the entire ship monstrosity.

My PS2 broke mid-Suikoden V and I haven't been able to fix it yet. I don't bother with Playstation emulators either, because I have yet to find one that works without jumping through an immense amount of hoops. The first half (or third, I'm not entirely sure how far I got) was very good though.

Suikoden Tactics and Tierkreis are mere distractions in my eyes. Tactics was good, for a tactics game, but served as nothing more than a sleight-of-hand trick while they worked on Suikoden V. Tierkreis is, well, I am not entirely sure what it is. It is a decent game but fails in most of the major departments of being a Suikoden game.