Affiliate Income vs. Adsense [Which is Best?]

If you rely solely on Adsense then you are in danger because you rely on one company for your revenue. If Google decides to drop you (and it happens without reason) then your business is shattered overnight.

If Adsense starts paying less then your business suffers greatly.

If you diversify by ADDING different income streams in addition to Adsense, then you are in a stronger position should any income stream dry up. It also gives you more money to invest and grow your business.

The results with affiliate marketing is the same with Adsense. It is not quick money and it requires hard work developing traffic.

Adsense will stop paying you well if you stop getting targeted traffic, just in the same way that affiliate revenue dries up. There's really little distinction so I'm not sure what you are getting at.

Affiliate marketing is harder, requires more attention, marketing knowledge and understanding of user behaviour. That's why most people don't do well with it. They do what they know with Adsense - throw up a banner - and then it doesn't work.

Affiliate marketing requires a bit more manual labor, but with the tools out today it is exceptionally minimal and just requires a change in editorial policy to discuss products and show people where to buy (using aff. links) and for me it out pays Adsense every time. That doesn't mean I have dropped Adsense, I now earn about 3-5x more by using different sources of income.