Honestly, every clan is balanced, but some clans could be trash for one person, while it's OP for another.
For example, Khan's Guard is the only Khuzait class with a 2H weapon that can swing, making it hard for a 2H lover like me to get started. I have to loot it first and earn the money to buy Khan's guard, and then I must sustain it. So either get my money from TRYING to hit my arrows before going in Rambo style, or risk starting from scratch.
What I would recommend, and it's just an idea, not fleshed out:
A; 1 customizable class per faction
Have an editor where you can choose whether you want to be infantry, ranged, or cavalry and then pick your weapons.
The game will calculate the value of your class then, which will be the price
This way, every faction will have at least one class that suits you, and maybe a relatively decent cost to sustain.
B; Have preferences
When searching for a game, you can choose which clan(s) you want to be in, or which clan(s) you really want to avoid.
Of course, these preferences could affect how long you must wait for a match, but at least you know you won't enter a game as Khuza--I mean, a clan you despise.