I had an Avon on the rear of my bike that I didn't like as it wore - it had a tendancy to skid under braking on wet surfaces. However, when losing grip it was predictable.

I switched to a Pirrelli Diablo Rosso. Words can describe how much I hate this tyre. It's rubbish and, I think, contributed to my first crash in 15 years of riding. I know now of quite a few drivers who have crashed in similar circumstances to mine (losing the back end of the bike) and all have been riding Diblo Rosso's. All are experienced and responsible bikers too and know how to scrub in a tyre before pushing it.