I ended up getting 8x, 10x, and 12x all in 42mm. I was expecting to lean towards the 12x myself. Haven't been hunting with them yet, but my wife strongly prefers the 8x for general nature viewing. Easier target acquision and larger FOV. I think if I could only choose one, I would go 10x. As is, we sold the 10x, and are keeping the 8x and 12x. The way I'd describe the difference is that the 8x are just much easier to use. Exit pupil is more forgiving, you don't have to hold them quite as steady, and they just appear a little brighter (to my eyes). But 12x will definitely get you more detail (especially on a tripod), but they're just harder to use to get that detail.
I am thinking of trading the 8x42 for a 8x32, but want to compare both first.