Source: Google Images
Mybenta.com is a huge competitor of olx.ph, currently these websites are legendary in terms of number of users. Too much users will also increase the competition among sellers. Thus as an alternative, you can check out these 5 alternatives
ClassiPH.com - A newcomer on the classified ads industry with very minimal design but useful. The website loads really fast. Also it is mobile friendly, you can access it with your mobile phone. The thing that I like with ClassiPH is their real time chat. It is really useful for seller & buyer as well. ClassiPH has 94% pagespeed score on gtmetrix.com and 93/100 on Google Insights
Dabest.PH - A very professional looking website which is worthy of respect. It is mobile friendly as well. It reminds of of the old sulit.com.ph for its usefulness
Sulit.PH - Not to be confused with sulit.com.ph, this website looks good on mobile phone as well. The website uses Wordress Platform. The thing that I like with Sulit.PH is their "make offer or tawad". It is really convenient to buyer.
Juantambayan.com - An already established website with growing number of users. Juamtabayan is like an online shop to me. (e.g Lazada) I also like their layout using desktop browser. I commend the usefulness of Juantambayan.
Facebook.com - No explanation needed. Facebook groups / pages are enough to K.O. Mybenta and OLX