Firstly I would say that both are doing good business, as both sites have the same concept.
the first big difference is that quikr is an Indian startup, but OLX is an international firm which is working in more than 70 countries consistently .
so therefore it is clear that olx has much gains than quikr .
quikr has more than 15 million visitors per month where as OLX has more than 80 million visitors every month, so its we can easily say that OLX can be trusted easily.
The third difference is that OLX has the policy of C2C that is customer to customer relation where a buyer van meet seller directly, but its totally different on quikr, as quikr doesn’t has C2C policy, so buyer cant meet seller.
Therefore I prefer OLX rather than quikr.
hope the above tips helps you.
Thank you.