I was botting Flesh Crawlers at earning about 35k EXP/H, but they are really crowded.
In order to get to Experiments you must have started "Creature of Fenkenstrain". They are decent EXP as well, but not the best.
You could also do Soul Wars, if you're botting of course.
I don't know how effective Ghouls would be with 1 defence, but if you have a good supply of food, there is a bank close by and is really easy to bot.
In P2P worlds, the Minotaurs are not very crowded and you will get like 25k EXP/H without difficulty. Once again, I only recommend this if you're botting.
There are plenty of places, so just "trial and error" every couple hours on different monsters.