I had the occasion to use both these websites to find a Buyer for my Car, in September 2016.
Within a few hours of posting, I had received a couple of inquiries on OLX and after a month I had received 8 offers.
Whereas, within a day of posting, a Pune - Quikr Evaluator contacted me, did a check-up, took pictures, and "Verified" my advt on Quikr, for a cost of Rs.1000-00. But I did not receive any inquiry till the end of the week, and on completion of One month, I have received One Inquiry only.
After posting on Quikr, I started getting many Credit Card Offer and other Telecaller Sale calls, and many more calls from Quikr Call Centres and Telecallers, asking me to Pay up more to upgrade my Advt on Quikr, which I flatly refused, considering my recent loss of 1000Rs with the Quikr Evaluator(Pune).
So with this experience I would definitely say that OLX is better than Quikr.