Random motion with an optical (or jitteriness) is pften caused by the surface you are using it on. Experiment. Many pads work poorly for opticals. I use my bare desktop, despite its wood grain. It could be lower scan rate or lower precision design, but I would focus on the surface first.

I use a Logitech MX300. Nice simple ambidextrous design, but with the higher grade scanning. I don't like bulky or misshapen designs that are the norm anymore. Rule #1: if I can't use it with easily in either hand, then it doesn't belong on my desktop.