I really liked the first and the second one.
But my favorite would be the fifth one. It really felt like a real Major Battle.
If any of you ever Romance Of the Three Kingdoms, yeah. I like the fifth and second one the most.

The third and fourth one was really boring.
The major battle in the third one stunk for me.
It felt like those missions where you can choose more than one party, and trying to fight different bosses for each one.
The fourth one was just plain boring.
I didn't try for any of the Major battles in the fourth one, and still won.

My Favorite person ever in these major battles is either Zerase or Shu. They rock my socks 8)

Second one and fifth one. They're a little similar, but I don't mind since fun is fun. Though my favorite battles in those games would be the attacks on Greenhill in 2 and the first attempt to capture Lymselia in 5.

Suikoden I and Suikoden II.
Both have their good moments and even though Suikoden I came down to a rock, scissors, paper thing, it was still fun with all the special things you could do, such as spying, dragons and thievery.

Suikoden V was good, but a bit choppy at points. Especially the animations lacked good points.