Hmm, I think I can cover some of this for you.

I might recommend Suikoden II. The music is absolutely beautiful, it has a great story (although its more political, not sure if that's a turn off for you), and it has a wide cast of characters, some very memorable. It has 108 characters so they can't all be memorable but the ones who stick out are wonderfully written. They are customizable, but some characters just have their strengths. I suppose there isn't much in the way of differentiating though. Suikoden V is also a strong contender, the characters and story aren't quite as strong as II, and its slow to get going, but its still a great game.

I haven't played all of it, but FFIV covers the part of each character having assigned roles. So far there has been a strong story and a strong cast of characters to it, but like I said, I haven't finished it, so maybe someone else could chime in more on that one.