My favorite faction has to be the Getai. I love the Greek way of warfare and i love the way the barbarians came to war so naturally i am really drawn to this faction. You get a flexible pike phalanx with some very nice barbarian type shock infantry. Their calvary is decent but with the mix of barbarian shock troops and the phalanx you can decimate many!

After the Getai i love KH, its the greeks at their best. If i had to pick a complete barbarian faction to play it would be the Sweboz. They were really worked on for 1.0 so they look great and i just love their barbarian units compared to the casse or averni. I really never liked rome in general but there are times when i love to fight with their infantry. Hope this gave some insight!