I would qualify my response with the caveat that after certain minimum standards of brightness and clarity were met, the deciding factor in my decision between brands almost always comes down to one thing:
As a long time eye glass wearer, nothing causes me greater fatigue than not having enough eye relief. The vignetting that goes along with having to align binocs close to my face frustrates me and over long periods of glassing for game, it drives me nuts. That's not a good thing when you're holding a 30-06...
The longer the eye relief, the quicker I can bring my binocular into play when I spot an instant of movement. Whether I'm birding or hunting, it's that ability to get the binocular lined up quickly with my pupil for maximum field of view that determines whether or not I spot my prey or my bird.
Again, that comes after minimum standards of brightness and clarity have been met. Eye relief is the biggie that causes me to spend my money.
It's the same thing with a rifle scope. If I'm packing a .22 in the field and hunting squirrels, you can bet it has a long eye relief fixed 4x28 scope on it. If the eye relief is long enough, you can practically start aiming before the rifle hits your shoulder--that split instant you gain before the squirrel ducks behind the trunk will put more stock in my pot than a 3x9 with short eye relief.
With a high powered rifle, that extra half inch of eye relief makes me a much better long distance shooter and I don't have to worry about recoil causing the scope to hit my eyebrow.
Yup, the older I get, the more I appreciate the comfort that long eye relief brings...