I have just purchased 2200 KHs. I have been impresed by speed (and simplicity) of C-Cex. Also, if they would be total scam, nobody would bother to DDOS them.

Buying PFC at AllCrypt, depositing to HashProfit and buying KHs with PFC seems to be best. But promo codes are not bad either. Use HPE241214.

https://hashprofit.com/en/khs/?hp=205653