I prefer 10x binos to get as much reach as I can and I just use my 6x rangefinder for closer (typically bowhunting) situations
I'm using 8x right now but would be happy with either. the 8x will give a little bigger field of view if that matters.
Either work. I was talked into a 8x and have been happy with it. Field of view is bigger. I have an old pair of 10x. I really can't tell a huge difference between them personally. Get a good set of either 10x or 8x. You'll be happy with either. Vortex has some good optics. I have a pair of leupold that I like. Probably would have went with vortex with their prices and how happy people seem to be with them.
with either 8 or 10x, recommend getting the best quality glass you can. for me that makes more difference than a couple x of magnification.
Both will work just fine.. myself I prefer a variable magnification binoc... lower mag for scouting and finding em where the larger field of view helps... then if I want to count his whiskers I can zoom in .... just get good ones... nothing is worse then going afield and your optics fog or don't focus well...