I'm about to hit lvl 9, and the units I've been using so far is Bowmen, Priests, 3 stacks with Bears, Ancient Bears and Polar Bears
The bears are really slow, but their crits are just insane, and they can soak up a LOT of dmg. I'm gonna replace my priests with Orc Shamans as soon as I can.
Just my 2 cents. /Zogun