This is a good place to ask since there are so many fellow sluts who have been with 100's or thousands of guys.
I've seen two guys that had monster cocks. Well over 12 inches. One was black and one was white. Bigger than anything I've ever seen in porn. Thick and long too. Both tired to fuck me, but the condom made it too uncomfortable to go past the head. The black guy was at a pron theater in NYC and the white guy was from a personals ad.
The smallest I've ever seen were smaller than a pinky. I've seen a white guy, Asian and black all with micro dicks, and they have trouble keeping them hard too.