For lvl 40 I would recomend Dragons for a solo Ek but if u find a team you can go dragon lords too or even wyrms to get a lot of exp
In lvl 60~70 you can start going to lion rock and kill ancient scarab + roaring lions or going to bog raiders + mutated tigers in yalahar factory
In lvl 80+ you can hunt hydras, dragon lords (solo), wyrms (solo), Giant spiders and/or sea serpents.