TBH, what i think your after is a server around the 8-10X mark of exp, that leveling is a good speed to level with IMO, its not "fast" but not to "slow".
What most of us like (including me) is making items for when you start, ETC make new weapons rings bracers ETC for inbetweens euro ones, even from level7+ as people just go straight in for level 40+ with euro servers.
Quests dont really get people from lower levels, i would say about 25+ for your first quest was a good reasonable level.
Maybe one or 2 more caves for around the 10-20 levels then the same with the 20-30 ETC, think you get the idea slightly.
Boss mobs in caves are always a bonus, along with a sub boss.
Drops is another to get people, now i have found out (or figured out) that with the new 2.3 files, that people dont mind hunting hard for items, its more the "more essential" skills, for this i mean TDB for wars, people dont like the grinding and constant killing for this skill to get it at level 40+. Same for taos, most of the time its for spells like UE or Hallu and even Deva. Same applys to wizzies with things like FlameDisruptor (think yo uget the idea) but people like skills like Rage ProField, Curse, FlameField, Mirroring ETC skills to be rare and dont mind grinding for them skills.
This is what iv came across in my time on p servers, because with High Rate servers, Most of the spells drop really easy, so people have the chance to use them, so with spells like TDB, Deva, FC, gives all chars a chance to hunt with new spells, but at the same time dont over power the server, i dont mean just get boss mobs to drop hem either, i mean normal mobs you kill.
I hope this helps, no idea if people agree with me on this one or have a oppinion or 2 to add to it.
P.S sorry for the essay