All brands are going to be within the same price point. Icon sells their kits in stages, more or less as recommendations of parts they would feel would be required as you go up in stages. This also makes it a lot easier deciding or figuring out what parts are needed to achieve what you're after.
Fox & King shocks are progressively valved, being their background is offroad racing. Progressive valving is desgined for bigger, higher speed hits.
Icon shocks are digressively valved, being a much more suitable application for any daily driven vehicle. Offroad, the performance will be the same as Fox or King.
As far as brand reputably Icon as been around for the last 18+ years, all of their parts and manufactured and produced in Southern California.
One of the biggest things I like about Icon, is with every vehicle they produce parts for they have tested the limits of the factory suspension in various situations and from that information their engineers find the means of improving.