Ooh, interesting. Well, let's assume that 'beneficial impact' can go into negatives, and assess each accordingly.

I know that there is a difference between X-Factor-type-shows and Jersey Shore, but both seem to elevate fame for it's own sake; even where hard work and talent are not what is being rewarded. This has led to a whole generation(s) of kids valuing fame for it's own sake, rather than as a consequence of hard work. Definitely negative impact. We'll give this a -5 rating for 'beneficial impact'

Similarly, the music of girls aloud - this has created tunes I can happily bop along to when in the mood, but it's also meant Cheryl Cole, who most little girls (according to a recent survey) would like to grow up to be, so this creates the same problem as described in the first paragraph. We'll give this an arbitrary rating of -0.5, weighing up those two things...

The CoD series - hmm, perhaps there has been no negative impact other than the already-existing self-perpetuating desire for studios to churn out yet more of these types of games. HOWEVER, it's existence has no doubt also inspired some of the many smart people interested in game design to want to create more interesting video game experiences (think indie scene). So, perhaps in a way this has had beneficial impact of +2 (of course I'm being idealistic here).

Cakefarts get a 'beneficial impact' rating of 0, because that is precisely how long I want to think about cakefarts.

So, on that scale, CoD wins, I guess!