I prefer binance since im not using kucoin for a long time and i think they required to do KYC im not really sure but binance is still the best in terms of volume
In binance if you do limited trading then you are good as it does not require KYC. Also people do not prefer KYC because they do not know how exchanges can misuse the data and you may fall for it. So better to see unless if it highly reputable one than you can get your KYC done.