For starters, Kyber will initially be an Ethereum / ERC20 only exchange.  Further down the line they plan on introducing atomic swaps as their mode of cross-chain exchanging.  Blocknet will have atomic swaps as well.  Atomic swaps are great but are limited to blockchains that support them.  NVO will provide the ability to exchange with a greater variety of coins.  NVO will also provide a plugin system allowing new coins the ability to be listed as soon as their developers can write the code to plug them in.  No waiting for the exchange to get around to it and accept them.  So NVO will have a huge advantage by being able to provide liquidity to all new coins faster than any other exchange.