Arabian: [link]

Thoroughbred: [link]

Friesian: [link]

Anglo-Arab: [link]

Mustang: [link]

Nightmare: [link]

--
"So wait, I analyze the probability of the second plain of existence in my sleep, and you dream about chewtoys?!
~Me, talking to Arkay about dreams

"LOOK AT THAT PHONE! That is a SEXY phone!"
~Neko

My vote goes to the Friesian, just cause they look so wild and gorgeous lol. But it all depends on what you want nightmare to be. For a riding horse I'd say mustang, for a show horse I'd say Arabian...I'm not too fond of the thoroughbreds... Anglo-Arab would make a good coach horse...?

--
"Wow San you're handwriting looks just like mine!"
"Uh, Alex?"
"Yeah?"
"Those are your notes"
"Oh."

"Look out! He's got a daisy!"~Mr. Moist von Lipwig, A Discworld Novel: Making Money.