Bitcoin - the King coin
Peercoin - one of the first POS coins and underestimated
NEM - because ties to corporate projects (aim at provinding concrete real life applications)
Byteball - aim to solve scaling issue in new manner, unique and fair distribution scheme and ability to send anonymous tokens (black bytes)
IOTA - aim to solve scaling issue and no fees -> meant to support the Internet of Things and strong ties with the industry
Nimiq - browser-based blockchain. Mine coins and run a wallet in your browser. Even your mom would understand this. ICO is bloated though