The best ad engine plugin

Hi there

I am building a website for a new magazine and I need some help/advice on the best ad plugin to use.

Ideally it needs to be able to handle site wide ads (ads that will go across the whole site) as well as section specific ones (Aads that will just get displayed on a anything classifed as ‘News’ or ‘Motoring’ for example.

Does anyone know of a plugin which can achieve this, or at least give me something to work with?

Thanks

Nick