As far as I remember, until Binance became the first exchange, Poloniex was really very cool. Now, from the point of view of generalization, I think that Poloniex should have its popularity and it seems to me that this exchange after it was bought from her has success in any case.
Crypto's growth is very fast and Poloniex is too slow to adapt, this is what makes them lose a lot of opportunities, and I'm sure it's hard to be top 10 if they are still like now.
And they haven't changed much even as compared to other exchanges. They still are using the same old approach. Bittrex on the other hand is keeping up with newer exchanges Poloniex is just losing users and volume. There are just a few coins I don't find anywhere else in a legit exchange that makes me revisit the exchange. They are turning into cryptopia.