I think the worst of the Anthrax series was #3 (I know, they're all the same dosage)... I managed to about half put my arm down the sleeve of my uniform blouse before I couldn't hardly move it...lol
Worst overall was the penicillin shot - feeling the penicillin oozing into your body and traveling down the back of your leg (or at least, thinking you feel it)... In BMT, everyone had to get the Penicillin shot. We formed up to march back to the barracks, took two steps forward and our TI put us at "at ease march" so the entire flight could limp home... Good times, good times...
Best experience with a needle was when I went in for knee surgery. The nurse had 30+ years of experience. I couldn't even feel a poke from the IV needle as she inserted it.
In the end, I don't like needles...but I learned to just not watch.