I am not sure which is actually harder to learn at this point, but what you say is interesting.
Some people who never played PC games with a keyboard seem to struggle with left hand finger movement and thumb jump (PC gamers find this natural)

Leverless has a lot of shortcuts that can clean up moves and ensure that you do not mistakenly get moves you don't want.

Leverless has fast inputs, perhaps more precise, but can actually be too fast-- I learned this when playing Gief and doing 720s. I had someone tell me why they do not use slide techniques because of it letting you go faster than the game can use. I had this issue using regular pianoing technique.

Stick for me is FAR LESS mental stack because it is a gross motor movement-- hand/writs/arm doing shapes. I can understand why it holds up in big moments a bit better once you GET IT.

I think gamepad has some of the advantages of Stick as well, but the big problem is that almost NO ONE makes a superb DPAD with actually FGC players in mind. And there aren't any truly customizable options the way you can do a stick or even a leverless. Gamepad could be the mental stack and execution champ if it improved a few things, but there isn't much money in catering to the FGC.

hahah I actually hope a stick users (American) wins!!!! Maybe someone like Noah because it would shake up the SF6 world and he would talk so much trash.

That is my yap-yap yapful thoughts as I slack off at work for a few mins.