Generally speaking, the more affiliates promoting an offer, the harder it is as an affiliate to do well with that merchant.
Check out this awesome list of affiliate networks!
By the way, if you look at the site of Stats Remote you’ll see they sell a program which helps you track stats on those networks. It automatically logs in and updates your cost on Google/Yahoo/MSN and also checks your commissions on all the networks.
Currently, I’m using Stats Junky which accomplishes the same purpose, but hosts fewer programs.
Those are the best two on the market from my research. It saves a lot of time when you have all the stats at your fingertips, without having to log in. They also do some pretty useful graphing of commissions, cost, profit, etc per day or month.