I'm not really all that interested in seeking out new feeds just for the sake of having more stuff to add to my account, so I just gave most of these sites a cursory look. The sites that I've subscribed to are those that were already of some interest to me before. If I stumble across another interesting one, on my own or from someone's recommendation, I might go ahead and it, but if I went searching for news just for the sake of having them, then I'd probably never leave.
If I were seeking out additional feeds to add though, of the sites given in this exercise, I would probably go with bloglines or technorati. They seemed a little more coherent to me. Syndic8's setup didn't make much sense to me, but that may be my fault, being new to the RSS world.