If Binance was smooth and good for you why are you looking for an alternative? Anyway, the altcoin exchanges that are pretty okay based on my experience and are decently reputable are Huobi Global(HBG), OKEx, and probably Bittrex(though I haven't used it in a year). But as always, do your due diligence when it comes to any exchanges.
Thank you for your valuable suggestion and the reason I am looking for alternative is for the fact that not all the altcoins or token will be listed in Binance as it will cost them a fortune hence if I have to work for a project with limited budget I want to know the best exchange as well as trading platform which we can depend upon. It will also help me choosing the right platform to trade if the desired coin is not listed in binance.