I played all classes but i'm dedicated cavalry and i don't have any problem about enemy cavalry when i play other classes because i know what to do, people should learn what to do against cavalries and (in general) should learn how to use their own classes advantages. Every class has advantages and disadvantages if you're using them well, then you're a good player. If you are not, you can keep whining. But before whining about other classes think this ''what if you're doing something wrong?''. There are so many cavalries but only few of them can dominate scoreboard and playing good.
Edit : In summary, no class is OP. cRPG is about your own game style and your own build, there are good players and bad players.