In my opinion Bitterex and Binance will be the best for sure. If anybody will be want choose good he should choose one of these two.
I see poloniex is popular but I have not yet burst into it
Because poloniex is not what it used to be. When it was good it was highly ranked and most valuable coin always find its way to be listed. They were good with pumping any coin on it, also aware of the american laws about security token, well paid before listing and good volume for market. I hope even binance can stay at the top of its game for at least 3 years.