~snip~
Of course the few things that one looks into have been said by other members, of which I will point out the ones I like:
1. No KYC would be best, but maybe that is no longer possible.
2. A quick response support team active 24x7
3. Responsive UI on both web and mobile, maybe a mobile app too, but is secondary for starters.
4. Discounts for loyal users.

^ These are the perfect answers, but I am not sure about the number 4 if there is. If someone avoiding KYC verification I think Decentralized exchange or a quick one is P2P exchanges. But I prefer an exchange that has a high volume of all coins to trade and the last one is security and must have to build a strong reputation from their traders. Nevertheless, all of these were found on FAQ and TOS of the exchange sites, just read first before you deposit.