Hello, I am trying to figure out which ad provider should I use, so what are you suggesting? AdMob, Startapp, Unity ads or something else? But im more into banner ads, so does unity ads even provide banners? And also I have no idea how to set up ads, I tried with Startapp, but for some reason it didnt worked, so maybe you know also some good tutorials which show how to set up ads? Thank you 
The one I used for my game was Unity Ads. It worked for me but it doesnt have banner ads only video ads. If i were you I would go for AdMob as it provides banners and has some tutorials online (on google or youtube) on how to set it up.
Hope this helps