Banner Ads? Better to cut out the middleman. Maybe develop a backend newsletter to market to people if not B2C. I hear there is a plugin to help your site sell your own ads, creating competition between advertisers. Ill see if I can find it again. Google Adsense lots of people still use, but its not 2010 anymore, though they are paying 75% now I think I read.
I have idea for serving ads that will be SaaS in the future, just have to make some seed money (10 mill) to go custom everything with the help of programmers.