Finally i got every single Hero on Max Level so now i can tell you their Dmg and Speed.
I will list the name and then 1. attack & Speed 2. attack & speed and so on.

Well atleast that was my plan until i realized im too lazy to list them all.
If you are wondering if any Heros are special or more valuable. Nope.
Theres only 1 Hero that is a must have - Dragon.
Unique 1 Second cooldown Tier 2 Attack (6,5 Million per second)

Maybe i could tell you which (more expensive) Heros have an 3s Tier 2 attack (only the last attack).

Bear: 3s, 83,5 Million Dmg
Frog: 3s, 31,6 Million Dmg
Flowergirl: 3s, 9,5 Million Dmg

All other Heros have an 4 second cooldown BUT there are even worse ones.
Dont buy: Sheep(5s), Squirrel(5s), AsianDragon, Fairy, Rat, scorpion, squid (bad cooldown times 5-15 sec)

And if you wonder about Anglerfish and Bat, Anglerfish is really bad - Bear and Gryffin are way better
Bat has the most powerful 4 second attack (112 Million) but other than that nothing special. And its really expensive.

Heros which i used: Penguin, Bee, Dragon, Flowergirl, Robot, Demon, Frog, Bear and Bat. By the way:
you want to farm money on Stage 499 - 500. When you´re Dragon is atleast Stage Sexy 2 it should be able
to destroy every monster within 1 second (afk farming). Another tip is : Only buy 1 stage of the active bonuses
for example "French Girl Charm" = Stage 1: 50% more Hero DPS. Stage 2 only gives +5% so its a waste.
You dont need any other active bonuses.

Well thats it so far. Have fun with the game ^^