Universal thumb throttles are the most versatile throttle installing on either the right or the left and are the most popular. They also work well on trikes and drop bars using Handle Bob mounts.
Universal Deluxe thumb throttles have add a built-in clamp allowing them to be installed or removed without removing grips and other handlebar accessories. This makes them ideal for switching between Class 1, Class 2, and Class 3 ebike classifications for different legal throttle requirements. This throttle also has excellent modulation (smooth ramping).
Left and right wrist throttles are preferred by some, especially motorcycle riders. They come with ergonomic grips with palm rests. (They sometimes require modifications to rapid shifters so that they clear the throttle.)
Left and right thumb throttles extend down and have a natural horizontal thumb action. They have excellent throttle modulation.