Balanced server eh? I'd call it balanced as long as there's no changes on the skills, max level 99/70 trans 99 stats, and no custom / edited items. Rates, I don't see what should be defined as balanced here. As long as I find the rates interesting for a casual player like me, I'll go drop in.
Moving to other stuff, about 3rd classes, I don't hate it. I love it, but not for WoE (especially pre-renewal). They look cute though <3! About customs, let's say item, I would see first. If it's like ALLSTAT+5, Demihuman Reduct above 12%, I won't bother hopping since my thought about balanced item is peaking at Bapho Horns, I Love China, Alice Doll (it means, if the custom items' effect are MUCH better than those, I'd call it imbalanced). Features such as quests, depends. If it's for making gears, I'd look for those that provides not-really-grindy and mostly soloable (since I'm mostly coming alone), as well as the economy. For quests like role-playing, I'm kinda picky on it since "kill x mob y times" or "get x pieces of y items" is pretty much the same as normal PvMing.
Then last is community. I'm NOT interested in a server which community doesn't speak English in public, the people are not communicative and friendly (including staffs), or have a dead forum, in which the posting rate is like 1 post/day. And yep, PvP/BG/WoE community attracts me more than PvM-Leveling ones, in which I usually ends up on mid-high rate servers.
Dat it? >: