Anyways, here's what I had to say: [slightly modified]
....While it's true old friendships were helped a lot by proximity and circumstance, that does not mean they weren't your closest friends. It's only that time and space have slowly broken those bonds away... but if you would see them now, would you not immediately be extremely close with them again?
I've been fortunate to go to college and then live right near the same yeshiva most of my good high school friends now attend, keeping those friendships strong and intact. At the same time, there is definitely a difference in the relationship I have with some of them versus the others.
A few of my best friends live scattered throughout the world - I almost never speak to them, let alone see them, but whenever we speak, it is as if we've been roommates and/or together the whole time. I think that perhaps those are the closest friends - the ones who would come rushing to my aid (or I to theirs) if the need arose, even if we haven't spoken in a year.
As an aside, there are also the friends we have for different purposes - some to confide in, some to ask advice from, etc. They often overlap, but they also often do not...