I like the second option, with it going up, but I think it could go either way. Go with what you like.

Are the frames equal on all sides? If yes, the choice is yours. If there is one side of the frame heavier/wider than the others, I would say that is the bottom.

I like the first option. It seems like the subject is centered in that image. Whereas in the second option it looks like the subject is too close to the top frame. But I’m weird about things being equal or centered.

The first is the historically correct orientation.

The second orientation looks unbalanced. First one looks right.

I say the one on the right because, in that orientation, the bottom rail of the sash is wider/taller, like this:

I think the 2nd option. I see two love birds kissing (or is it one choir singer with mouth open wide?)

It’s the 2/3 1/3 ratio weighted to the bottom, which is the classic design principle used in art today. The 1/3 2/3 is top heavy and awkward. And wrong.

I know nothing but I picked the first one right away.

bbkieffer, I can see that opera singer in the second one. ;-)

I'll just leave this here as this was my first thought...............

Phylogeny recapitulates ontology. Heterochrony anyway.

Flowers are reproductive organs. And were often used euphemistically so as to be more genteel. Georgia O’Keeffe ‘s paintings aren’t so much about pistils and stamens for sure.

at this point i'd just resell them. every guest will be thinking all these things whether they say them out loud or not. (and yeah, my mind went to millworkman's photo and georgia o'keefe first thing too.)

besides, they are too small for your existing windows.

The first pic would be the accurate orientation by the looks of the pattern itself and the framing of the glass.
Are you planning on setting them into the windows in the pics? The stained glass looks awfully small to fill those windows, like you will have to frame them in a lot.

It does seem you could use more stained glass and less framing

Hanging those from eye hooks with a chain can work to use them as artwork. But if the intent is to use those as actual windows, that will need new custom glass created and installed correctly as a sort of interior storm window.

The first is the correct orientation. As Sophie said, it's a flower.

Demon or female anatomy. Install as shown.

Yin, yang, you mah thang

Consider NOT installing the window as a window; instead you could either have the glass reframed or just refinish the current frame and then hang it inside your existing window as a stained glass window hanging.

http://www.sabatropics.com/stained-glass-window-hangings/large-stained-glass-window-hangings-stained-glass-window-stained-glass-window-hangings-minimalist-design-pictures/

http://bcell2016.org/stained-glass-window-hangings/perfect-stained-glass-window-hangings-h4642627-stain-glass-window-hanging-hanging-stained-glass-window-angel-stained-glass-window-hangings/

http://imged.me/img/

Checking for stained glass window hangings on line might give you some insight as you decide which side you should hang as the top.

The first.