the new horses are all free/wild; as they can be found wild or being ridden by npcs. so no, none of them are better then the horses you listed. in fact there's only 3 horses breeds in the story mode game with a 10 speed: fox trotter, thoroughbred, and nokota; and all 3 of those need to be purchased. 

the new horses are warped brindle arabian, few spot appaloosa, perlino andalusian, red chestnut arabian, buttermilk buckskin kentucky saddler, liver chestnut morgan and gold palomino tennessee walker.