I like BLX90 more. K90's hoop is too stiff, it doesn't flex well for off centre shots, so BLX90 works better for my 1HBH, volleys, and spin serves. Also the "feel" people get from K90 is mostly shockwaves. It's pretty damn sweet when I go for a big forehand with K90, but I can definitely feel the shockwave being transferred to my arm. I've never have elbow trouble with PS85 and n90, but K90 hurt my elbow.
I don't get all the hate for BLX90, I think it takes the good aspects of n90 and k90 and combined into one. I think people need to give it a chance, I think you'll like it too.
That being said I think BLX is just wilson's tech for lowering the production costs of rackets as basalt+carbon hybrid are cheaper than pure carbon fibres. They simply modified the flex of k90 and turn it into blx90