I think that currently 1v1 pvp isn't balanced at all...but in my opinion the top 3 pvp classes for duels are:

1. Vanguard
   
2. Occultist
   
3. Blademaster
   

I agree with you @Dark R0z0k, they should work on the balance for pvp here, but those classes are the best for duels no question, especially Blademaster imo.

I think that the best PVP classes are Druid. In fact, it depends on what you like but I think that druids are the best. the second class is the warriors that it follows very close!