From a publishers point of view: I prefer AdToll because they have fantastic support and will help you select the format that is suited towards your website. However AdToll is based on that you have to 'sell' your own website which just requires good traffic and a good alexa ranking. Also AdToll lets you specify your price for showing an ad on your website. I have not had a good experience with AdBrite and they also have a quite slow reporting system, however you would only use AdBrite if you have an excessive amount of trafic. Thus AdToll is better
I dont like the fact that AdBrite has few format ad options. I believe they only have the 200x350, leader banner, etc. They dont even carry the uber popular 125x 125 ad size format. A minor issue really, just a personal pet peeve of mine.