As a producer, I'm very happy with JuicyAds. I've yet to have another banner/text ad sponsor make me as much as they do. Payouts have been on time and without any hassle.
More importantly, I think, is that I spend a couple $K every month on buying banner spots on different sites within the JuicyAds network. If you pay attention to the stats provided on each page (i.e. check out what traffic is clicking on the banners, CTR, etc.) and have good looking banners, you will do very well.
As with any ad campaign, if your banners are weak, you'll get very little clicks and I doubt you'll see your moneys worth. Definitely pays to know what you're doing before throwing a wad of money at something (though don't get me wrong, I wouldn't throw the wad back at ya
).