You basically have 3 choices:
1) Find a local dealer for a national brand with a good reputation in your area and leave everything to him or her. Big names include Rainsoft and Kinetico. Expensive but carefree if your dealer knows what he's doing.
2) Find a local dealer who builds his own branded systems from components. Big names in control valves include Clack and Fleck. Less expensive than the proprietary systems in (1), carefree if your dealer knows what he's doing.
3) Find a local or Internet vendor who will sell you the parts to build your own system. Several names pop up regularly on this forum, including ohiopurewater.com, qualitywaterforless.com, freshwatersystems.com, discountwatersofteners.com, cleanwaterstore.com. Read through other threads here and look at some websites to get a flavor for what a DIY project entails. Minor regular attention required on your part once you know what your're doing. Basic plumbing skills and common sense are prerequisites.
First thing to do, regardless of your treatment choice, is to get a comprehensive water analysis. If you're on a municipal system, they can provide that. If you're on a well, check with your county extension office (http://bowie.agrilife.org/) for sources for testing. Texas A&M does that (http://soiltesting.tamu.edu/). Also determine your softened water need (gallons per day, average and peak) and see if there are any local laws governing softener use (or not).