Well etherdelta is borderline a scam.
https://www.reddit.com/r/EtherDelta/ Their reddit is now full of people complaining that they lost their ETH, granted some of them did fuck up but still. They basically have no support team.
Cex.io is also just slow as fuck right now, 30 days and still no verification and their website is so fucking slow sometimes, I don't know if it's just me.
Bittrex is also again just borderline scam, I got verified after insisting for a month and still thousands and thousands of disabled accounts, I personally wouldn't trust them ever.
Binance is good, although sometimes my withdrawals do take quite some time to process.
Poloniex also worked flawlessly for me.
But yeah, it seems that the influx of new users is affecting all exchanges, which shows their lack of preparation for what they are doing.