My favourite (ie essential) accessory is the flash flipper ..without that I cannot produce shadowless pictures with on camera flash. Thats my No1 No 2 is the 3rd pary accessory grip--- I makes the camera look more posy but I dont use it for its intended purpose.....The one under my D800 carries 4 spare AA batteries for the flash and the one under the D7100 a spare EN EL 15.....keeps my jacket pockets free of clutter 3rd is the harness that lets me carry two cameras one on each shoulder and does not slip off ...keeps my hands free to work the crowd..
Most hated ....is any flash gun ....Why can they not make it bleep after its taken a shot ..then I would know its ON when I have gone from inside to outside and forgot? My camera bleeps when its focused ... Even a light that stays on all the time when its ON would be helpfull.