Nice customs and pictures, Wolf Knight! I like your green klicky in general, but I do agree with Martin that the other klicky looks more like a leader due to his more extensive armor and battle scars. I'm also not sure I like the green klicky mixed in with all the purple klickies, as he looks not like the leader of the group but from a different faction entirely.
On the whole, your purple barbarians look much more fantastical than your Gauls, due to the former's helmets. Your Gauls look quite authentic and the different helmet (the Viking-style one) helps distinguish the leader.
I distinguish my chieftains not by making them more heavily armored than their warriors, but by giving them gold accessories rather than silver. This, of course, is not really authentic, as the the cheiftains would have iron swords, helmets, and armor and would be more heavily armored than their warriors, but it's Playmobil and it works for me.