Well, I have been complimented many times on my balls and scrotum (which is very active and responsive). I am usually a B, but easily become an A when aroused or in cold water. I am a good C when relaxed in the heat or sun. I have some good examples (pics), if anyone is interested. At the beach, laying out, I can go from a C to an A and back to a C, by going in the water and then drying in the sun after, for a little while.
Group A I think to be honest normally, ever since I was young, my testicles are pretty small anyway and usually barely visable and quite a few people including both relatives and friends have commented on them to! Sometimes if I'm lucky though and it's warm enough and they have been fondled and pulled long enough, then they do hang down a little more after swelling, so maybe just about a 'B'. I have used cock rings and ball weights in the past, very tricky to fit and not ideal as I haven't been able to find any small enough to stay on in comfort for more than five minutes sadly!
Im in between A Group and B Group .
My balls tend to hang just a little bit under my cock when I'm flaccid. With the tip of my cock lining up with the top of my testicles.
I also think it's common for the left testicle to be a bit lower than the right one on guys.