1) For popunders, use
Plugrush (they pay a little more, than the other ones),
Ero Advertising (most of them open up to for times per 24 hours for the same IP, unlike the other ones), and
Traffic Shop.
2) Mobile redirection is very good, especially if you chain several websites into one (something like
Plugrush ->
Juicy Ads ->
Sex Goes Mobile), but if you dont want to use it, I would recommend
Bitter Strawberry,
Exoclick,
Sex Goes Mobile, or
First Mobile Cash.
3) For regular banner ads, go with
Ero Advertising (they are very good for this),
Exoclick, or
Juicy Ads.
4) If you decide to purchase traffic, what a lot of people do (and profit), use one of the following ones (or several of them at the same time):
Traffic Shop,
Traffic Holder, or
Ava Traffic. With this, it is very important to know how to do it, and how to measure the results (analytics, and server logs).