If I loved the first Advance Wars game, will I enjoy this one?
If you enjoyed Advance Wars, you'll like Valkyria Chronicles.
If you didn't enjoy Advance Wars, you'll also like Valkyria Chronicles.
OR ELSE.
Just pick who you think you'd like. Just realize certain people will like to be paired with certain others and will get a boost if you do have them in your active squad. The opposite can also happen, they can get a stat decrease when with certain others as well. Also, many characters will be good/bad with certain terrain types, which may influence who you use on a particular map.
It's not just slight bonuses or penalties. Linked/bonus attacks from characters that like each other are pretty important.