Ball + collar - With a thread neck and a hair tail, the hair is much more secure with a collar. With no collar, the hair is stacked on itself instead of around the collar. This makes it much more likely to pull out. While I tied Kip tail with no collar for years, I've switched to a ball collar. It is just an easier process to tie in and secure the hair. With a collar, I have to tie in the hair usually 2 times to cover the circumference of the collar. My fat fingers prevent me from spreading the hair completely around the collar in 1 shot.

Ball no collar - Versatile! You can tie any type of jig with it!