I like fursavers, and wish I could get colored ones, but my pups are wearing smaller sizes that are hard to find in long links, let alone long links with colors. They are Aeri and Kes' 'working' collars for IPO.
Aeri, Kes, and Snipe all like balls on a rope, but I'm kind of picky - I like handles that don't rip up my hands, knotted ends vs. loops or toggles, and chuckit ball sized or smaller. Squishy is better for Kes and Snipe, more solid for Aeri.