widgetbucks and bidvertiser are no where near to adsense !... i would prefer .. adbrite, tribalfusion and kontera... nothing else !...
the only problem i faced with other advertisers other than adsense is that there is not enough ads like google. most of the time there is no ads. but I also really looking for adsense alternatives.
I'm currently only using Google adsense and TLA for my sites... Adtoll will be a good choice as well.
Adlandpro with its pay per impression is still next to adsense.. http://myseoblog.net/2008/02/29/lists-of-advertising-networks/