ive never played as:
Aedui- always liked Arverni more
Carthage-idk y always wanted to but havent mayb next campaign will b them =)
Pahlava-wanted to just cuz there Persia but never did (cant stand nomads)
Sauromatae-cant stand nomads
Ptolemaioi-always been more of a fan of the Arche
makedonia-dont know why loved them in RTW but not so much in EB
getai-close to the top of wanting to play but havent gotten around to it =)

factions ive only played a few turns of:
Casse-first time playin just to test it got pwned by rebels ><
Epirus-second shot at the game got pwned by Arche
Roma-started playin it but gave up i still have the save so i may keep goin w/ it later
Saba-cool faction but in debt from start of the game and too many rebels around them
arverni-just started my second campaign w/ them first one Aedui/Roma ate me up this time im watchin my money more carefully =p
Lusotana-(just started the campaign)
Hayasdan-started playin but Arche slaughtered me
Pontos-took a few settelments then bam 3 stacks of Arche troops march in and conquer my half stack army and small garrison troops (263 BC)
Saka-banckrupt with 3 settelments and only 2 units in each settelment (2 generals in homeland and 1 general and a horse archer in other 2)
Sweboz-just started campagin and its a blast so far

Factions i acctually got somewhere:
Arche-playin now loved them in RTW love them now
Baktria-got really far to like 213 then constant CTD and Arche/Saka slaughtered me
KH-love almost beatin only have to deal w/ Roma, Ptolmaioi, and Carthage and im done