I think most of us know how they smoke. Comparing a 1 hose Mya to a Km is a tad ridiculous, they are much different designs. Myas are basically meant to be used with multiple hoses in my opinion, they are great for that.
You only need one style of KM, I would say the Tri-Metal, it's the most common model. All of the KM's are designed the same internally so they will all smoke the same. None of them are "The Best KM" as that is based in the eye of the beholder.
I could give an unbiased review of all those hookahs right now based on personal experience.
I guess a documented trial would be good.
How will you be comparing them? Based on ease of pull?