Bittrex and Binance are centralized exchanges. This means that they function as a 3rd party between a buyer and seller. The issue with centralized exchanges is trust. You do not know if they can be hacked, go bankrupt, or simply take your funds and run to the Bahamas. Waves has a decentralized exchange (DEX), which allows peer to peer trading without needing a 3rd party. The Waves decentral network (nodes) will verify transactions for only 0.003 Waves as a fee. As there is one common truth on the decentralized blockchain, it cannot be hacked and no 3rd party is in control of your funds.

There are also some other pros for a DEX:

1) low transation fees: a DEX does not need a margin to cover costs that a centralized exchange has (e.g. profit margin, employees, facilities etc.)
2) fast transactions: with the Waves NG algoritm, the DEX can handle mass transactions volumes
3) Secure network: A decentral network of nodes is less likely to fail running, compared to a central server from a 3rd party
4) No central gonvernance: A DEX cannot be shut down by a central goverment or institution

See also the following link that explains how DEX is working.

https://coinsutra.com/decentralized-vs-centralized-crypto-exchange/