As I understand matters, the 'best' Leica models are, in decreasing order of excellence:
(1) Noctivid
(2) Ultravid
(3) Trinovid. This model itself has three marks:
- HD
- BN
- BA
The rangefinder model is the Geovid.
(For Swarovski, the range goes: NL Pure ('best') → SLC → EL, and the rangefinder model is the EL.)
I mean to write a boring post at some stage on modern binoculars. My take on them is that at the end of the '80s modern computer-controlled milling led to a step increase in the quality (and quality control) of lenses. Therefore, anything from the end of the '80s/ early '90s, from the big 3, should be perfectly acceptable in terms of magnification and quality even today. Because they are sealed units, modern binoculars do not suffer the fogging and prism or lens displacement issues of older binoculars.
The two major advancements since then have been in reducing the weight of binoculars and integrating rangefinders into the units. However, improvements in the lenses (and their coatings) have been iterative, and minor at best. Quite how much a hunter will appreciate the practical difference between a Trinovid BN over a BA is a moot point. Both of these marks are still highly regarded.
As regards the marketing of binoculars, Leica seems to have moved to a 'latest model' strategy, in the hope that customers will want the latest and most expensive models. However, if you are prepared to put up with a small increase in weight, it seems to me that there is no reason why you should not buy an older model.
Also: given that the machine tools used to mill the lenses are computer-controlled, there ought to be very little difference in quality between a mid-market brand and the high-end brand. As far as I can see, this is right: a Leica or Swarovski is a better pair of binoculars than - say - a Pentax; but whether the former is worth 5 or 6 times the latter is very dubious. My Swarovski ELs have lasted me, so far, some 30 years of heavy use and been repaired once for free, and I sincerely doubt that I would get that life out of a mid-market brand, with the exception of the
Noblex BG/A series (I had a pair of these, which some bastard stole).
Good second tier manufacturers would be Noblex (ex Docter, ex Carl Zeiss Jena), Opticron - I have experience of these two - plus Meopta, and so on.
Finally, there are many perverts who like to look at birds and - if you have ever seen them - they buy themselves the most hugely expensive telescopes and binoculars. If you are prepared to wait a bit and lurk around eBay and auction sites you can often find older, well-treated, optics at a fraction of the new price.