I'm a Chrome user. Best results I got was all individual ads by any business who pays. These are the ads that clutter up the Kijiji pages and render Kijiji a waste of time to review. My filter did not remove the "per page" banner ad (that horizontal multiple ad), nor multiple posts by individuals who don't pay. It delivered a big improvement.
My filter was...
Note: the "," between the elements being blocked (just cut and paste the whole line).
Again, it does not remove the "banner ad" on pages, nor ads by users who post multiple ads for free.
However, I can actually use Kijiji again.