Never KYC unless it's a high street exchange, preferably an american or european one that's regulated.
Anyone else, give them darks or find a way to trade without KYC. If you give them KYC docs you run the risk of identity theft or worse (Bitfinex customers receiving letters of lithuanian banks they never heard of because exchange staff used their docs to open bank accounts lol).
Okex used to literally PRETEND to do KYC so i just put a random passport number during KYC, a fake name and they approved the account without asking for any photos of the IDs lol. Many such exchanges that don't︀ verify anything, they just pretend to do KYC.