Everyone else is at Angkor Wat, Bayon and Ta Phrom, so that means you’ll have a really hard time getting good photos there. It’s basically impossible at Bayon.
There is hardly at anyone at Banteay Kdie, which is on the “short circuit” just after Ta Phrom.
Aside from the lack of people, I felt it was actually the most photogenic temple (maybe tied with Bayon) due to the relatively small size and the symmetry throughout. It has these well-defined rectangular structures inside. Maybe also due to the fact that it’s in the jungle so not too much light affecting photos taken from the wrong angle.
I had never even heard of this temple but definitely recommend a stop here!