Poloniex has not really impressed me in the last few years as this exchange has very few coins and poor liquidity is the main reason I feel satisfied. I think at present Binance is still a very good choice for investors and you can freely trade here without any problems. Poloniex used to be the number one exchange in the past, but after a long hiatus, this exchange was only a small exchange.
If you weren't impressed by Poloniex few years ago, then no chance for you to get impressed now. Either you are new to crypto trading or not easy to get impressed. It's a favorite centralized exchange few years ago beside bittrex, now the time has changed and I agree that Binance is one most popular exchange to use even though it is maybe not the best exchange that most decentralized people are looking for.
I think it is depending on the personal preference of the user who is using a certain platform, We do have different taste and the best exchange platform that we consider is the one we can freely move and it is the exchange that is better than the other, It might give you good service, good promotion, good customer care or other reason that you are impressed with.