I have a pair of Minox 15s, and optically, they are very good.
Not as good as the Kaibabs or Swaros, but at half the price of Kaibabs for 97% of the optical quality, the Minox are a bargain.
If you are talking about dedicated open country hunting, where you will use them a lot every year, spend the money and get the better glass. If you just want to try out the ?big eyes? style of hunting, maybe need them for one hunt, the Minox will serve you well.
I purchased mine for an open country Mule deer hunt a few years back. I was able to spend hours on end looking through them with NO eye strain.
Your best bet is to find a place where you can look through all three side by side. There IS a difference, but not much. The bigger difference is the size and weight.