I don’t see it mentioned often, but basically my favorite has been the GameCube controller. Massive primary button with the secondary button the same shape but smaller and next to it, with the alternate (X/Y) buttons a different shape that flow around the primary, all in easy reach but all different to the touch. Especially when I’m playing the Xbox or Switch for a while and then switch to playing the other I’m messed up on the controllers for a little while since Nintendo and Microsoft swap the A and B buttons but both keep A as the primary button (I think a legacy of the original NES/Famicom putting the A button closer to the right hand and the B button farther in, to the left of the A).
I’d prefer the right thumb stick to be the same shape as the left, and it needs a left shoulder button, but beyond that I’d pretty much keep the layout as-is, maybe a slightly different size/shape to better fit in hands. I’ve seen a few third-party controllers like that for the Switch but haven’t looked into them enough to buy one.