I actively use Binance & Cryptopia, and also have an account with Bittrex that I haven't really used. It can be a bit frustrating be cause certain coins will only be available on certain exchanges, (like HitBTC has a pair I want to trade, but I don't want to make an account with them just yet...).

I like Binance's back-end and system, it's very clean and easy to use. I used to trade Forex, so I feel like these are still lagging behind currency charts/indices (price isn't always clear on the charts with the cursor, etc).

Cryptopia I use because it allows local currency and is sort of the "gateway" into using/buying other coins/tokens/ICOs/etc.