Something relevant to note, is that YC's two biggest successes got into YC at least in part because of personal relationships. IIRC, Dropbox was recommended by former roommates and friends from MIT (Xobni guys?). Airbnb was recommended by Michael Seibel from Justin.tv, perhaps others. In both cases it's possible that YC wouldn't have interviewed or perhaps accepted one or both of these companies if not for those reco…
Maybe Dropbox and Airbnb wouldn't have succeeded without those recommendations, but those recommendations could certainly have led to a MORE merit based process. When it comes to judging quality, it can sometime be hard to beat a personal opinion from someone you trust. That may narrow the field a little bit (nobody has personally experienced all the alternatives) but it may also improve your decision.