I live in a town that has a small dealer that routinely allows customers to set up several of their spotting scopes on tripods in their parking lot outside their shop to judge differences for themselves. I chose the Swaro and Leica in their 80mm, non-HD configuration for my own personal test. We were looking at hikers on a mountain trail approx. one mile away.
Choosing glass is a very personal thing. Color distortion, clarity, amount of definition, darkness at the edges and ease of focus all just a few things to consider. After 15-20 minutes of side-by-side comparisons, the retailer brought out a Kowa in 80mm. By then several more customers were involved in my "taste test". Each had their own idea of pros and cons for each scope. For most of us, the Kowa held it's own against these formidable players for a little less than 2/3rds the cost of the better known brands. I bought the Kowa and never looked back.
I also use a luepold 12-40X60 HD and love its packability. Backed up with Leica's 10-42 ultravids.