First, you get to diminishing returns with bins just like knives when you get to the upper extreme of price points. There they tend to be optimized for specific functions and usage.
I have Leica NV (Noctovid), a couple Zeiss bins and I'm looking for an HT 8x32 and 10x54, GPO are excellent values for a premium bins near an Alpha bin experience at a more modest price (my demo's were only $400), and then there is Steiner.
I find Steiner "big" bins are the best for use with eyeglasses. I have the classic "tank commander" versions in 7X50 and 8x56. The little 8x30 versions are super handy. The thing that makes them so good for eyeglasses is the infinite focus and reasonable eye relief. They are also tough as hell so, good for rougher usage.
Kowa Promar are good but, similar quality is available in GPO and costs less.
I have some Minox bins no longer made that are the full equal of Alpha bins from Zeiss, Leica and, Swarovski.
For what it is worth, the "flat field" bins, Zeiss SF, Swarovski NL Pure, and Leica NV can be a love it or hate it thing. The "flat field" optics have a huge Field of View but, the bowling ball effect bothers some people. I like the softer transition to the edge of traditional bins but, the flat field is nice for birds in flight or any movement on the ground like deer or sheep on a mountain.
I'm not going to drop $3K+ for these new flat field bins because I can get a really wide field of view with a softer edge which I like just as well or a bit better depending on the day for under $2K in a gently used pair of bins. Swarovski to me are a bit more expensive and there are so many variations in optical coatings and features, I have avoided them. I seem to always find better quality at a lower price with Zeiss and every once and a while Leica. Leica are demanding of eye position so, use with eyeglasses is more difficult to learn but is certainly do-able.
For sheer value, I used to think Zeiss Terra HD was where it was at but, today GPO is where I would spend my money on a ~$400 set of bins. That's not to say Kowa and similar brands are bad but, optical performance and construction of the GPO series is simply better at the same price point.
Steiner is in a category all its own if you are talking about the classic Military bins. The 8x30, 7x50, and 8x56 are super hard use bins and have excellent performance in early dawn and fading dusk light. The also have good resolution at night. These are what I generally take in my SxS UTV or my tractor.
Speaking of night, a good set of bins will let you see stuff at night you cannot see with the naked eye. If you are young, you want a 7mm exit pupil but, most older folks are physically limited to a 5mm or 6mm pupil dilation so, get lighter binoculars if your eye cannot use the larger exit pupil. A 7x42 will be easier to hold and weigh less than a 7x50 for example.
Then there are specialty bins like my 6x30 Kowa Promars which are great for close up use and have a wide field of view for nearby tree limbs. Think Butterflies, Bees, and Hummingbirds!
GPO bins from the Cameraland NY demo list are great values in my experience for bins that look and feel new with only the slightest hint someone looked through them.
The only Alpha bin I want that I have not owned or used is the Zeiss HT. If someone has one, I can make a good trade on some gently used Leica NV bins!
