[Firehouse]

Please don't say that quality and quantity are incompatible. Picking one over the other is a fool's choice; you might as well choose between air and water.
The highest quality guys - however you want to measure that - are generally attracted to the most successful fraternity chapters becasue that's where they find the greatest number of other guys like themselves. Too often, fraternities that are not popular and are not able to draw the numbers necessery to sustain themselves or even compete, tell themselves that they are "exclusive". It's not exclusive if nobody wants to join.
The concept of "large" is relative to the individual campus. If the most highy regarded chapters have around 50 men more or less, then that becomes the standard. But if the top houses have 100 and yours has only 50, you will never be able to sustain effective competition against them, for sports, for girls, for the top rushees, for anything. You might have an exceptional group of 50 and they may defeat all the 100-man fraternities. But you can't do it for long. You have no bench strength. Every man has to do everything, and that wears everyone out. If you stop to take a breath, or slow down, or make one mistake - one bad pledge class - you will fall into a lower tier.
In that scenario, 50 is "small" and 100 is "large". On another campus, 50 is large and 10 is small. I come from a campus where everyone who is decent has 100 members, and if that's all you have you're probably not competitive, or "small".
Some chapters choose not to compete, and that's fine. When I pledged we were small and uncompetitive. When I finally graduated we were on top. I can tell you that brotherhood is enhanced when you're a member of the winning team.
And another thing as long as I'm on a rant. It's fantasy to think that the large chapters have little brotherhood compared to the small, and that their alumni are not active or supportive. I raise money for a living, and I can assure you that the most successful undergraduate chapters produce the most successful and generous alumni.
End of rant.