Judging by the results we see here in the office, and anecdotal evidence from colleagues, I would recommend a sonic toothbrush over a rotary toothbrush regardless of the commercial brand. the bristles on a rotary brush cover a smaller area and in m opinion require more dexterity to be effective. Rotary brushes are great if you are a dental hygienist but for most people the bristle arrangement of the sonic brushes more closely resemble the toothbrushes we grew up using.
In addition, I like the massaging effect the bristles of a sonic brush have on our gum tissue. A sonic brush used with light pressure n the gums as well as the teeth can have a tremendous impact in reducing inflammation of the gums, provided the teeth are cleaned from of calculus (tartar).
If you find yourself having trouble moving to an electronic or ultrasonic toothbrush and would like to hang on to your traditional toothbrush, I would recommend that you use extra soft or ultra soft bristles.