These are the top two 10x50 binos currently on the market, as you rightfully say (at least if we ignore for the moment the new Nikon WX).
For my eyes, the Swaro is top in terms of clarity and wow effect; many users will agree on this, some will not.
Resolution is so good in both binos that for all practical purposes, there is no winner here.
The Leica wins in my eyes when it comes to color saturation - and again, many users prefer it because of this. The image of the Swaro appears noticeably cooler to me.
The Leica and the Swaro are about the same size, the same weight and both deliver superior optical and mechanical performance. The main difference between the two is
- in terms of ergonomics: the Leica has a single hinge, the Swaro a double hinge. You will find partisans for either design
- in terms of image rendering: the Swaro shows the best off-axis sharpness with its flat field image, the Leica doesn't use flat field optics and shows noticeably less edge sharpness. For astro uses, this gives the Swaro an advantage, and in fact the Leica is not very common in the astro community.
For birding, however, edge sharpness is not necessarily something you need, and I know birders who don't like the flat field of the Swaro and prefer the optics of the Leica.
Of the roughly 20 other 10x50 quality binos currently on the market in Europe, none IMHO delivers performance equivalent to the top two. But some are really very good, like the Fujinon 10x50, although with its individual focus it is mainly useful for astro.
The Docter Nobilem is unfortunately not on the market anymore; I do very much like the Meopta MeoStar 10x50 which I find has an excellent price/ performance ratio (like most Meoptas, btw).
As mentioned, the Nikon WX will blow everything else away - also in terms of price! - but it is a dedicated astro binocular.
For what it's worth.
Canip