My favourite is Binance still. I've used OKEx, Kraken, KuCoin and Bittrex mostly in the past years. And they are all fairly good. It all depends on what you want to buy, and for how much.
There are lots of other new exchanges that I've never heard about when checking Coinmarketcap or similar. Mostly are full of fake volume, so rather just keep to the main ones. And not the ones from some dodgy little Island paradise where it is more likely they will scam you at any point.

You can find some other exchanges here also (https://gocryptowise.com/exchanges/).