I'm really tempted to get a centurion or a dragon mech, as I do not currently own a medium mech and I love being mobile! I know a dragon is actually a heavy mech but I feel it should be played like a medium!
Never tried a Centurion but Dragons are one of my favs. My usual rides are Fang and Flame but these are good. The first is actually an identical build to what I run on the Fang: