as long as their KYC is not hard to complete also their support and interface are good enough then it wont problem for me, currently I'm using 2 platforms for trading cryptocurrency and till now there's nothing problem when I used them. I suggest you use top exchange so you wont get in trouble like weak support, low liquidity, etc.
Normally a KYC can be done in different levels the lower the levels the easier to complete the KYC process but the higher the complicated it takes. Support is important because we are dealing with money on here and we are confident if they can respond quick to solve our issues.
The interface can be next with support because it is how comfortable we are when we do our trading activities. If we can trade on desktop and on mobile is a plus point for them but may I know if what are the 2 platforms your using? But, by the factors that you list I believe the exchange your using is binance and kucoin, am I right? Because, these 2 exchanges are so far the best when comes to features and user experience.