It may highly depend on the niche of your site. You should try both and you'll se which one works better for you.
Adbrite is horrible do not waste your time unless you are interested in having ads on proxified pages on a proxy. For everything else use Adsense.
Why would anyone use Adbrite??? I've had many sites with Adbrite on then and every single time the earning were less than reasonable. Adsense is still by far the only viable option.
I have used both adsense & adbrite. I can assure you that Adsense is the best PPC ad network. Adbrite or any other network dont even come close when it comes to ad relevancy & payout.