The Boker Tree brand knives are reliably high-quality, in my experience.
There are some nice knives in the Plus line, but I've seen too many quality control issues with them to consider them worthy of the prices they demand. For example, I love the looks of the Burnley Kwaiken design, but mine featured a number of issues (most notably, the tip of the blade protruding significantly from the knife when closed, to the point of cutting fingers and clothing when used).
The Magnum knives can often be recognized as rebranded Chinese Sanrenmu/Bee/Enlan knives. Fit and finish, as well as overall quality of materials and construction can be sketchy on these knives overall. That said, some of them can be a great deal (e.g. the Enlan EL-01 is a great knife for $10, and paying double to get it labeled Boker to save yourself China-knife-shame is probably worth the money to some).