As a crypto enthusiast, I recommend the top exchangers namely: Binance, Poloniex, Bittrex and Cryptopia for BTC pair tokens. IDEX, Hotbit and Merca for ETH pair token. First of all, before signing up on these exchangers. Check first the Social Medias, Website of the token you want to sell for updates (date of listing, exchangers, whitepaper). Check FB, Twitter, or Reddit for the feedbacks, insights as well as FA & TA. Youtube is also the best alternative for reviews. Second & Lastly, always have a 2fa on the exchanger you are signing up. Being secured of your investment is the best tool for you away from the hackers.