Currently, the best creatures to hunt till you hit level 37~ are the undeads.
Skeleton Warrior, Zombie Plague are probably the most hunted creatures in Phobos due to their high exp and insane loot drop.
You can easily start hunting them at lower levels and climb your way with no issues and 100% guarantee profit.
So here is what I propose and that is coming from my experience.
Cut the exp from undead to 3/4 and nerf, if not remove at all most of their good loot drops and increase the penalty for level difference (meaning you will start losing exp at early levels)
Getting from level 10 to 35 by killing the same enemy is just... weird.
And it gets easier and easier the more you progress.
A balance between exp/profit is needed.
With the exp nerf, people would have to hunt other creatures to level, find loot and maybe even team hunt (it is obsolete at all on lower levels, at level 40+ it`s needed so you don`t start to lose money)
Thanks in advance.