I absolutely love my Wow Joy Pen, and REALLY wish that they made a left-hand version.
I got a Chinese knock-off for under $20 delivered.
They have stiff switches, which I switched out with replacements from an old Logitech ball mouse, and it was a big improvement.
I had an Evoluent and hated it, everything about it was all wrong, the biggest problem was that it was too upright. Neither vertical nor horizontal is best, in my opinion, I would estimate that the Joy Pen is a little more than 45 degrees upright.