I put in another vote for affiliate marketing. You have so many more options and as Rob already said, YOU set up and control the ads. Controlling the advertising is the biggest reason. With adsense your stuck with what they serve. And as already mentioned, there are SO many rules and terms for adsense. Doesn't take much to get rejected or your account closed. It's like it's ruled with an iron fist. Seems like it anyways.
Plus there is an almost endless supply of products you can promote as an affiliate. Well, depending on the niche. But for something like Internet Marketing, look how much is on JVzoo, clickbank, Warrior+. You won't have enough time in th day to promote everything there is.
Just as important, with adsense you put all your eggs in one greedy basket. With affiliate marketing, you can have multiple, multiple, multiple products and income streams.
Seems like this question comes up quite often.