Honestly, I find everything after ~Chicken to be pointless, unless I have a gold multiplier. I'll be at level 1000 and rebirthing before I get another girl maxed, unless I was over halfwayish to 1k before having to go to work/sleep. (I'm under the impression the rewards are simply linear, so there is no reason to go past 1k)

Currently I max (and have maxed "sexy"):
Frea
Raptor
Penguin
Panda
Monster
Monkey
Dragon
Snowfox
Turtle
Robot
Chicken*

*I can typically get to 1k w/o chicken, but I do get enough money to max her before hitting 1k.

FWIW, currently sitting on:
905 hearts
lowest shard count is 305
52 Amrita. (usually get at least 1 a day, more on weekends where I can upgrade the nymphs more efficiently. Stockpiling for if/when I need to max sexy other girls if/when the dungeons come out.)

(Oh, and PS. May as well max all the charms, there's nothing else to use hearts on.)