One point that you may want to consider is that a Netflix subscription + selected a la carte services is a powerful and cost-effective combo. In my household, Amazon & iTunes aren't in competition per se with Netflix. Netflix gets its monthly fee regardless. When the 3 year old wants to watch something, it's Netflix. When I'm browsing around, it's often Netflix. When we want something in particular and won't wait, it's Amazon or iTunes a la carte.

While I wouldn't mind if Netflix would start offering a la carte as well, personally it's not much of a bother. The videos play either way.

So the whole "vs" approach may not be the most accurate. I'm not limited to any one of them, and with a month of Netflix costing less than a single top-tier movie "purchase" on iTunes it's not hard to justify a bit of mix and match.