Assuming that you can only afford one pair of quality binoculars...
* If you hunt in thick stuff, then go with 8s or smaller.
* If you hunt primarily in thick stuff with somewhat regular hunts in open spaces, go with 10s.
* If you hunt primarily in open spaces, go with 12s or 15s.
No matter what route you go, there will be compromises if you use them outside your primary hunting area.
If you go out west, put whatever binocular you have on a tripod. Take two people with the same skill level and binoculars; one handholds the binoculars and the other uses a tripod. The tripod user will find more game than the one handholding his binoculars. More power to the those that glass with a spotter; tried that and it was not for me. I'll stick with my SLC 10s or 15s and pull out the STX when needed.
The clarity of glass has a greater impact on your ability to find game than magnification. I'd rather take my SLC 10s in the field to glass than a pair of 12x/15x Wal-Mart specials. Here are two real life examples:
1) Hunting axis deer in Hawaii. Could not see the herd with my Viper HD 8s. But I could see the herd very clearly with the guide's EL 8s. Same magnification but significantly different optical clarity.
2) Looked at a full moon with an old Vortex Nomad spotting scope. Saw enough detail to like what I saw (ignorance is bliss). Looked at the same moon (in order) with my Viper 8s, SLC 10s, and SLC 15s. Despite significantly less magnification than the Nomad, I saw a lot more detail due to better optical clarity. On a related note, my SLC 10s blew away the Vipers and the SLC 15s (thanks to additional magnification but same optical clarity) were better than the SLC 10s. On a more comparable magnification comparison, my STX 65 blew away the Nomad. The optical clarity was not even close. Then for grins I looked at the same moon with my STX 95. It was impressive.
