I am surprised no one has mentioned Pocketbits here. I have been using Pocketbits for a while and it has worked pretty well for me. I have used Zebpay and Koinex as well, but I have found Pocketbits to be the fastest by far. Generally they process KYC within an hour and Deposit and Withdrawals within a couple of hours. That's way less than the time taken by other exchanges. The support team is quick to respond and it's easy to reach them using the live support chat feature they have. They also support more coins than most of the other exchanges. Make sure you join their Telegram channel where you can get all the latest updates and support too, in case you decide to use their service.
Couple of hours for withdrawal is just great I think. But still regarding KYC the most convenient exchange is coinmonkey platform. As far as I know it is not an exchange exactly though it partners with major exchanges so you can use rates from major exchanges but st coinmonkey website without having actual accounts on these exhange a. As some guy told - jus like general store.