I think all of the factory colors are nice, and I usually don't like the idea of color changes unless it's a really nice color that was either never offered for the car, or a crappier version of that color was offered. And it's got to look like it came that way from the factory. For some reason I'm less opposed to painting a car that is currently black or white, I don't know why, I guess I'm weird that way. At least with black, if you don't paint the bay, or the area inside the car and you pull the carpet up or something, at least it's nice neutral black. The problem is - I love black cars and would probably never change one.
Pick a Mitsubishi color, or better yet, a color that Galants actually came in, even if we can't get them on our usdm vr4s. If you want blue, nordic blue is nice, or if you want red, do a red that other Galants could come in.
As far as value - will anyone ever realistically restore it to factory condition? One time I heard on a radio show that changing the color of a car really doesn't affect its value all that much; I was pretty surprised.