i have the power breed at 25, and i wish i had waited for a speed. power is a glass cannon, 1319 hp. mangle is useless in slot 2 for all breeds, and dodge is only useful for 325 speed breed. so power breed's only rotation is howl claw claw repeat... but in my experience he's dead before that second claw is cast.
speed breed on the other hand- same hp, but against any pet slower than 325 you can use block (slot 2), pounce (slot 3) with 'if strikes 1st' bonus which makes it hit for about the same as claw if it strikes 1st, and just like claw it has no cd (and has 5% higher hit %). slot 1 you can pick up counterstrike to have a 100% hit humanoid attack if needed, and it's an ability that can get a bonus hit if struck, in case the other pet is faster.
so speed does less damage from breed type and no howl bonus, but it has a useable 2-round dodge, and a 100% hit attack of a different type just in case.
MADORAN__ <WCP> Shakesbeard
___________<PP> Orcane, Shrecksar, Remoo