I’ll make an exception and be long-winded and digress…
Hold your thumb up at arms length, so that your thumbnail appears to cover a suitable sized object in the distance. Now shut your left eye. If your thumbnail still covers the object in the distance, you’re “right eyed”. If the thumbnail moves to one side, you’re “left eyed”. This is how archers tell which is their natural side for using a longbow.
If you stand with your feet side by side, about shoulder-width apart, and a friend pushes you suddenly from behind, one foot will go forward to stop you falling over. That is your ‘leading foot’. Some surfers/skateboarders suggest beginners do this simple test.
The point being that, in complex activities, it isn’t a simple case of being ‘left handed’ or ‘right handed’. Right handed people eat with their knife in the right hand and fork in the left; but if they only use a fork, they transfer it to the right, even though it is doing the same job. Left handed people tend not to transfer the fork from one hand to the other.
So, which is your ‘natural’ seat holding hand?
Do you usually hold the seat when you freemount? (I do.) Which hand do you use? I use the right hand, whether I am freemounting right foot or left foot down - which means I am doing a different set of movements if I mount right foot down from when I mount left foot down. It isn’t a simple mirror image.
I knew without any shadow of a doubt I would want a right handed handle.
If you need another test, I’d say ride along a floodbank (US = levy/levee - remember to give way to any Chevies you encounter, especially if the levy is particularly dry, as the occupants may have been drinking whiskey and rye and this could be the day that you die). Ride along the floodbank “hands free” and then turn to ride straight down the steep side. Which hand grabs the seat to slow you down?
If you don’t know then there are two possibilities:
(1) It would be premature to buy a handle, or…
(2) In this respect, you are ambidextrous and any old handle will do.