Honorable Mention: Sons of BraggCheap character unit that can spread out, has some great abilities, and are like more flexible champions. Great synergy since they can also accept other fell calls.
#3 Gatorman Witch DoctorAwesome utility support solo. Still bites like a gator, but brings some nifty magic abilities that are pretty accurate. He can have some fun with Sacrifical Strike on nearly-dead gatormen and making things undead and tough will be useful for other Hordes factions like Circle, Skorne, and Legion.
#2 Captain Farilor and StandardHe gets a bad rap because he's not as OMGWTFBBQ powerful as other UAs out there and he's a bit pricey. However, as a UA, he offers great survivability for the unit with a mini-feat in combination with defensive line making the Legionnaires ARM 20 for a turn, with set defense, and enemy spells are at -5 RNG when targeting them. He might not make them more killy, but Legion needed more survivability anyway.
#1 Gallows GroveCircle players all over the world get giddy when they see these guys. No surprise with a 1-point arc node that advance deploys. They make both Kruegers, Morvahna, Cassius (naturally) and especially Mohsar very happy. While they also offer entropic force, the 3" bubble makes taking advantage of this ability very situational. These guys will find their way into most Circle lists and they at least offer us a way of removing really obnoxious tough infantry if we really need to get a bead on the enemy warcaster/warlock.