After years of watching impression based Ad programs evolve, I think they are all fairly poor performers. AdSense actually worked years ago, now I think there are far better ways to monetize websites.
But if you must use an ad program, shareasale . com works well and pays their bills. It requires a little more work because you have to pick your advertisers, and most pay a commission on actual sales instead of by impression, but it is a stable company and I have used them as both advertiser and website owner.
You will noticed I did not include an affiliate link, just their website. I get nothing if you join and nothing if you don't. They are free to join. Hope this helps.