I sold a lot of binos in the central London camera store years ago. Buyers wanted the 10x rather than the 8x but most users prefer 8x. You magnify wobble too much at 10x.
With premium glass, the quality of the image holds right to the edge no fall off. They give much better contrast in low light and produce less internal flare.
When I was an employee, my job supplied me with binoculars of my choice. I went for Leica 10x42s. They were amazing - like suddenly having the vision of a buzzard when you put them up to your face: no perceptible distortion or dimming, no odd colour fringes. They were a touch heavy, though. Also, having got used to Leica quality, I knew I could never go back to anything less if I left the job. So I got a pair of secondhand Leica 8x32s for myself.
This was a great combination: lots of my work was surveying or observing farmland birds out of a car. You'd be looking over long distances, so the greater magnification of the 10s was helpful, while the weight didn't really matter: I wasn't carrying them round my neck. And if you're working out of a car or hide, you can generally steady your elbows on the window frame or use a short Finn stick.
When I wanted smaller binoculars to carry with me on foot, or if I was working in woodland, I'd use the 8s: small enough to fit in a pocket, light enough to carry around your neck and to hold steady 'freehand' with no problem.
I'm now freelance, so I only have the 8s (and a 'scope on permanent loan from a client). I don't really miss the 10s much.