Determine the needed flow rate of your home, how many gallons per minute. How many people are in the home and your water hardness is in grains per gallon. That information will get you the correct size machine. You do not want to lose any water pressure or run out of soft water.
The best water softener is one you can get parts and service on from a local dealer. Rainsoft, Culligan,Kinetico, Eco are all good brands but also stupid expensive.
Eco is the worlds largest manufacturer and makes Eco,Sears,General Electric,Whirlpool, Rayne, and North Star. North Star is typically marketed to plumbing contractors and the one I like the best. I've installed thousands over the years.
Water Boss has a bad reputation around the Houston area, No service support. The fact that they were sold by Home depot, Builders Square, Lowes etc. with no service support didn't help them.