ok i've to reconsider some of my opinions after trying more to play vs them.
Honestly if you always have a plan in your warband against legendary units you suddenly have a huge advantage (duh). My fault was not having a very consistent plan before against them and i was getting my sorry ass spanked. I do not know about wolven yet (although i will be soon using them deleting my lovely lion warband :'( ) but Lion and Ram have plenty of good solutions...however you must always have more than 1 threat/plan to beat a legendary, or you can forget it.
if i've to make a top 3 i would say:
chimera, worg , golem. however chimera and worg are pretty much on the same spot i would say...it depends on your team composition... the golem should be used more strategically as a living wall / defensive but all the players i faced used him as a worg and died pretty quickly. Can't say now if he is the worst one yet...we will see.
all in all i applaud the design team, making super units balanced / beatable is not easy