Well, i'd say it really depends on what you want to do with it. Personally, for me, I can't ride the XP's. They seem to just not dance as well as my M (for me, anyways). They have this wierd tendancy to not want to lay over, so you're fighting it, and them BLAMO, it's on it's side, and you're past the point of no return, stuck in the trees with pinecones all up in you chit....
But that's just me.... My M, though, seems really nimble, and super easy to "play" with. I rode a buddy's stock Apex MTX last year, and it surprised the heck outta me. For it's weight and size, it was VERRRY impressive and easy to throw around. That could be another option for you, as said.
I don't have any real personal experience with the Dragons, but the ones i've seen seemed pretty impressive. For my money, i'd buy another M8 in a heartbeat. BUT, shop the dealers too.