Culligan is one of the best. If not for the product, for their service. Read the fine print, after the $19 per month you are usually locked into a contract for around $70 - $120 per month. Also, many times with the trial period, if you have it removed after the three months, you have to pay the install charges. Not to say this is wrong, just be aware.
Rainsoft, at least in our area, is very high pressure over priced sales. Think a Kirby salesman on steroids if you let them in the door they will not leave without a signed contract. Make up the guest room.
The system I am looking at with Culligan has a RO (Reverse Osmosis) drinking water system for the kitchen also hooked up to the ice maker.