Wisps are still blue at 13, so Eurids Crossing is a good zone, as well as East
and West Commons.
Bandits in West Karana, or raiders in a full group (N Karana)
Dervs are camped, but plentiful. I much prefer bandits.
Smugglers in the Qeynos Sewers are tailor made for Enchanters. Loot's not
great though. If you get a party, hit the shark pit right next door.
Greater Skellies on the undead island (OOT) are fantastic experience and worth
1-5gp per shot. I have not encountered one that wasn't level 13, and I've
killed about 20 of them so far. Your Exp bar will visiblely move each kill.
I heard Aqua Gobs in OOT are good loot as well.
If you have a magic weapon, try Lavastorm in a group.

So many places to hunt, so little time. Hope this helps.