The expansion is very alt and offspec unfriendly nevertheless I managed to get 3 toons into 90
Druid (guardian / Resto)(alchemy / herbalism) | Rogue ( assasination / combat)(Skinning / leatherworking) | Mage ( frost / fire)(mining / tailoring)
now I am considering what is easy to level up and can help the other toons as well
I say Pally or Monk. pally being easier of course because its closer to 90. But that way you have another healer/tank to play with.Regardless of which you chose.