Super nymphs do main damage? lets see...
level 90, check
150k health per monster, check
18k per kill, check
19 nymphs unlocked, next one will cost 2M gold..
Someone mentioned, the level 2 costs/damage ratio is lower than buying next nymph, which is true... but by around level 4, leveling the Nymph has a better ratio IE, level 2 light mantis will give me 40 more damage for 620k, level 3 monkey (prev nymph) will give me 56 damage for 630 k, level 4 monster(prev nymph) will give 78 damage for 587 k, level 5 panda will give 128 damage for 685 k, and level 5 penguin gives 121 damage for 656 k

total nymph damage 13.3 k per second
level 12 cosmo damage (around 3-4 million, total gold spent) 466 damage per tap
2 super nymphs ..
Level 10 rat, 1.26 million damage every 15 seconds
level 10 phoenix (1 evolved), 3.1 million damage every 10 seconds
Yep, super nymphs are definitely the way to go- cost of 3 slot-5 hearts... so yes, the $20 starter is the way to go, if you are going to spend money- just don't reset as soon as possible, until someone lets us know if you keep shards/evolutions through a reset..