As for actually reaching the caps, only Franz manages to cap Spd before endgame (20/12 as GK, 20/14 as Paladin) while everyone else will cap one or two stats by 20/16 or above (Amelia caps Spd, Kyle caps Str, GK Forde caps Skl and Spd, Paladin Forde caps nothing).
So, yeah, both in story mode and post game, GK is the better option. If you want the +2 Mov so badly, use Seth or one of the flyers.
"In the darkest nightmare hour, when not moon nor sun has risen, I take Zelda in my power: I shall keep her in my prison!" ~ Ganon