Kensington ProFit K72421AM Mouse
I have always been a loyal user of Logitech products, and still find them good. However circumstances were such that I was pressed and had to choose another product. I was unsure of the quality of the Kensington unit, but after 3 months of day in, day out usage, it has performed flawlessly, what more can one say. It fits the hand comfortably and has a positive action. If any cons could be found, it might be that the side buttons are very sensitive and sometimes operate before you are aware. Easily corrected though.