in my experience, the biggest problem is just the fact that they are just as hard as anything else to paint for warmaster but you need to paint at least 6 warrior units. very monotonous. not a lot of figs for them to break up the look of them. The rangers and the thunderers are the hardest to paint, just as dave said, lots of pouches and clothes and other bits on their models. same with the slayers as the warriors, just a lot of repeat painting.
to break up the infantry strip and too randomize it is to actually cut the strips up and re-align them together randomly.
opposite of their basic 3 infantry units, the cannons and flame cannons and gyro's are very fun to paint as well as their characters (which are needed the least of all warmaster armies)