I've got a C7/A1 type upper on my lightweight carbine. the aperture it came with isn't marked, and I can't tell which side is for long range, and which is for close in.

I'm planning on swapping out the aperture, but there's a lot of choices out there aside from a new A1 or A2 aperture.

which aperture is most recommended around here?

I'm thinking about the XS aperture with the notch and peep in one...

get what ever you want. i like the A2 myself. the A1 will be what you have now. two small peeps.

no other opinions? I'm surprised. I guess I'll just drop an A2 in there, unless someone else pipes in with their favourite...

I have XS same-plane apertures on a 16" pencil carbine, with an XS skunk-stripe front sight.  It is a great arrangement, even for an old fart who otherwise would struggle to see iron sights.
I cannot imagine that that an open-notch rear could possibly work that close to your eye.  There is a reason that AKs mount their open sights halfway up the barrel!
I prefer the same plane sights as they give you a quicker battlesight when you're using the large aperture; the A2 large ap is meant for center-of-mass hits out to 200, but it makes hitting things smaller than a breadbox somewhat problematic at any distance.  As a result, I used the small ap for virtually everything when I had them on the carbine.  Actually, I still use the small ap for most things, but for acquiring a larger target in a hurry, the big hole is the way to go.  The black & white front sight is bunches easier to pick up against nearly any background, again helping speed and accuracy.
Moon