the quality of our home water is poor and I want to get a water filter
system. I cna find plenty of companies but no way to compare their
products or systems. I think we want reverse osmosis.

we are based in london, england

http://www.waterfiltercomparisons.com/Water_Filter_Comparison_Matrix.cfm

this web site gives you a good comparison of water filters
hope this is what you are looking for.

There is a water sysyem widely used in Japan & Korea. They call it a
water ionizer. For more information, check this website
www.rekoniser.com. Hope this will provide what you are looking for.