So far, my preference is Coinbase and trading with GDAX plus Poloniex for altcoins. I'm still exploring other exchanges, but it's a slow expansion with there being so much out there to explore such as ICOs and new tech etc. I can't get an account on Bittrex bc they don't offer it where I live yet. Also, I have noticed complaints from people on almost every platform I've heard of so I think they're somewhat competitive with slight pros/cons for each depending on preferences. I plan to add to this post, which I will post newly, so stay tuned! :D Am followin' ya, too, so we can share info!