The real deal is this. It is not the faction it is about the cheap Jade Dynasty Gold. Let us give you an example. You have 2 Factions 150 ascended exact same build. One has a 5 all his gear, the other has a 9 all his gear who are going to win? This game is designed so that if you spend real money you will be the best.
If you do not break out the credit card you will be average. Which faction will own most as an endgame pvp with correct tomes and skill and really nice refined gears also knowing when to use the skills in Jade Dynasty.
Speaking from a Vim perspective, your statement about Vims being the best is not true. Every class has its strengths and weaknesses. There is still faction to come out yet. Our advice, play what your play style is. We enjoy tanking, so we chose Vim (Balo is pretty much the same thing, just it is not a Human). Just play what fits you best, in the end it will come down to how well you have learned to play your faction, aka skill level (Jade Dynasty Gold).
Pros: high SP, ATK, far AOE, massive damage, variety of skill, and low chance of failure. Cons: not so high HP, DEF. If you get your armor correctly refined, you will have a really good chance of knocking that low def and hp out of the way just to go to average.