I can't stand Kraken, as they don't offer a lot of altcoins and have a shitty layout as far as ease of use goes.  Even exchanges like Yobit have better-looking websites than Kraken does, but I suppose that's just a matter of taste.

And man, Poloniex used to be one of the hottest exchanges out there--that should tell you how fickle people's opinions are as far as exchanges go  Nowadays you usually see people recommending Binance above all and see very little mention of Poloniex.  But as a US-based person, options are kind of limited these days if you don't want to do KYC.