I've done the upper canyon twice & the lower once, all as photo tours. The upper canyon has a flat, sand floor, easy to hike, but usually very crowded - there are multiple touring companies all doing tours at the same time. As others mentioned, the photo tours are best, at least for photographers. The guides know when to be at different locations for the best light, and they will hold up the other tours to let you take photos (within reason!)
The lower canyon is more rugged with built in staircases/ladders in several locations. Far less crowded, particularly if you go early in the morning. I didn't find the lighting as interesting as it was at the upper canyon. When I was there there were no guides - you paid & they turned you loose for a couple of hours.
I have a page on my website with lots of photos and information that might be helpful:
Antelope Canyon.
Upper Antelope Canyon
