24-32
Ordelle's Caves @ the large room with Beetles, Rabbits, and leeches near H-8 on the first map
I mostly used pets and prey of the same type vs each other. (i.e beetle vs beetle). Chains in the beginning were fast, chain 4-5 common with some kills over 200xp. A missed charm with a large pool of mobs that link could be fatal! Everything seems to link only by sound here and only leeches aggro. Carry a RR scroll. Beetle jaws and leech blood sells pretty well for starting player gil. 30+ exp slowed a bit but it was still about 3K exp with each clear of the room. Early on this might support 2 bst's but 28+ I was just clearing the room when the first mobs started to respawn. 2 bst's would hurt each others exp.
I tried the same tactic with higher level beetles further inside but the others all aggro and became a bit of a pain at times plus people farming keys started coming in so I moved back. At 32 exp dropped to 80 or less per kill but was still easy fast exp. Could probably stay here to 34 but I grew tired of seeing the same thing for 8 levels.
A friend leveling with a decent exp party in qufim got left behind here by a few levels with how quickly exp was coming in for me. We were both 26 and when I hit 32 he was only halfway through 29. Now I'm back to looking for another decent camp