It is short-sighted to think that if your GLO is "top-tier" then you can afford to look down your nose at the others. The fact of the matter is that the Greek system has always had, and continues to have, enemies who would like nothing better than to do away with ALL of us.
Our best defense is to be strong - to offer a way of college life that embraces the widest possible variety of women, that can offer sisterhood to women of all backgrounds, religions, races and economic means, that seeks to embody in our day to day living the fine words and noble sentiments we have as our creeds, symphonies, and statements of purpose.
The problem with rankings is that they are based on a very narrow set of data - it might be number of members, or chapters, or what have you, but it simply cannot measure the subjective things that can make a smaller chapter or sorority great in their own way. And most of the "ranking" I've seen nowadays tends to be TOTALLY subjective and based on individual perceptions - my personal favorite? When fraternity men base it on the perceived "hotness" of particular chapters. Yep, I've checked - hotness of members is not mentioned as an atribute of any NPC members that I've seen. It could be under the heading of membership selection, but I doubt it . . .
There are several chapters of NPC sororities at highly competitive schools that do not participate in formal recruitment. I have nothing but respect for the fact that their HQs recognize that while they may not be able to compete in formal recruitment, they still have something to offer to women who might otherwise not have a sorority home.
Also, those women who might not find a home during formal recruitment but who have a great deal to offer a GLO - what of them? You need only review recruitment threads here to see that the system is not perfect, and lovely, smart, talented young women can go bidless. It is not in their best interests - or NPC sororities - to become fixated on meeting the needs of a miniscule number of perceived "top tier" types. That would be our death knell. The system's strength is our best insurance that we will be able to pass our legacy on to generations to come.