Barbarians Can kill faster then most my enemies As Rome, However its true they break faster, Its because of their fighting style and Barbarism for the most part, The macedonians need to be flanked And killed in order to be defeated because frontally all your gonna get is the spear, the Barbarians will just charge at your line, giving you awesome opportunities To flank them. they rout faster but their Aggressive nature can cost you more men, Unlike the macedonians, who need to dedicate LOTS of time with thier static formations and spears against the 1.7 meter tall roman shields.
I've always looked on Battles against the savages as being the least epic and the hardest :/ When you just click the "End battle" Button another hoard of pedo bears springs out of those forests, and your like "AWWW NOT AGAIN" Also, I've never been a fan of european battlefield terrain
Most recently, My favourite and Epic-est of battles were the Ptolemic ones, The soundtracks make this game an absolute masterpiece. Give the Ptolemic Campaign a shot, It has a Mild lack of battles but Its amazing, and once again, the campaign and battles soundtracks are just awesome