Most Popular to Least Popular:
1. Assassin Cross
2. Champion
3. Paladin
4. Creator
5. Lord Knight
6. Sniper
7. High Priest
8. Clown/Gypsy
9. High Wizard
10. Stalker/Professor/Whitesmith/Star Gladiator/Soul Linker
Of course, this is by my own observations, feel free to go with what other people say.
We have tried to fix GTB and try and nerf it, but alias, the server bribed people to vote against change. Whitesmith imo isn't bad, but what I dislike about it is if you're going to use Cart Term, you're going to have a lot of trouble multi-tasking by spamming yggs, inflicting damage, watching your HP bar, watching your surroundings, and not to mention switching equipment.
I also agree with what you say with making PvP combinations that aren't popular, popular. I've done it once on a secret wizard. It was fun for a bit. Asura strike wiz + surviving 3 sinxs on me, along with 1.5k matk (which is enough to spam).