I believe that there is not enough electricity on earth for many proof of work coins.
From this basic hypothesis, Bitcoin will dominate POW coins. Coins like SYS coin are doing the smart long term thing. They merge mine with Bitcoin.
If you believe in POS model, my intuition is to go DPOS like Bitshares. This considerably reduces the power of colluding whales on the network.
The POW vs POS discussion merits a whole post on its own.