I can ONLY use a Kensington Expert Mouse for any length of time.
With the proper accelleration, you can throw the cursor to the other side of the screen, and then have immediate microscopic manipulation. Which an incredibly small amount of finger and almost NO wrist movement.
Thumb to left click, ring or pinky to right click, first and middle finger to control the ball.
I don't like the other trackballs because they are too small or do not have upper buttons. The larger the ball, the more fine tuned your small movements can be.
They cost $90 and are worth every penny.