I think I have a tie..the first time EVER was getting nailed flat in the front of the knee. Was at a dude ranch (vacation type trail rides etc) with my Girl Scout troop and I was on the fast ride. The horse in front of mine stopped dead for whatever reason and even though I had a good distance I had no where to go due to heavy trees on either side of the trail and couldn't stop my horse in time. The horse that stopped took exception to my horse running into his tail end and let loose with a hard kick that caught me in the knee. Wouldn/t have been as bad but I rode another 4 miles at a canter and hand gallop without saying anything.
The other time was when I was bringing a horse in from the paddock and the other horse didn't like the fact I was taking her friend away. I knew this mare and had never had any reason to think I couldn/t turn my back on her...she trampled me, literally knocked me down and went over top of me and she wasn/t trying to jump over. Caught me in the knee, arm and right temple...fortunately they were all glancing blows. Maybe what was funny, at least as I look back on it, I lost my glasses and I have vision where if I don/t have my glasses I nearly need a guide dog. I got up, took the leadline off the mare I had been leading and went after the horse that trampled me...of course, I couldn't actually SEE the mare, just this orangey colored big blur (chestnut )...still, I managed to nail her good a few times with the end of the lead line. Then I had to go back and try and locate my glasses :) found them, unbroken and not scratched but it took a good 35 mnutes.