Why price should be associated to ether ?

Project are lot different. Different targets.

Zcash have good capitalization market and it's young compared to monero or ether (supported by samsung/ibm and other big).
Zcash 19th in graduatory.

2   Ethereum Ethereum   $28,097,858,304   $299.15   93,926,278 ETH   
13   Monero Monero           $744,162,550           $49.88   14,919,655 XMR   
19   Zcash Zcash           $446,762,919           $230.54   1,937,931 ZEC