I have done few trades on Cryptopia and all of them went smooth for me so I didn't contact their support system ever. So on the basis of user experience, I can say Cryptopia is good. But as you saying they are not customer friendly then you can try others.
Best way to find good exchange is by searching your coin on CoinMarketCap. First search your coin, then open 'Markets' tab and list of exchanges where coin is listed will appear. Just select one having maximum supply and volume and that's all.