Arverni- simply prefer Aedui
Lusotannan- don't know why, but I always get bored really quickly with those guys, even though they should be fun with their nice units and all.

Have had troubles with Saka Rauka, by the time the economy got going I had a handful of family members (and nothing else) that had to repel Pahlavan stack of doom or get crushed. Was in 1.0 though, since they no longer start at war with Pahlava it seems they might be easy enough for me to get going with now.