I personally use Binance and Yobit because of thst fact that both of these platforms are widely accepted by everyone. I once used Poliniex and I must say that it offers a great experience as well. If you want assurance, go for Binance and Yobit. 100% legit.
I just chose Binance because this exchange has a lot of potentials for you to make a profit here, and when using this exchange, all your trades can happen very fast without spending too much time waiting. Also, I also use more Huobi because many people appreciate this exchange, and the liquidity here really always makes me feel very impressed.