We have had our Aquasana undercounter water filter for over 10 years. The water has always tasted pure and clean. We would never use or trust anything else.
Pros: Clean taste, Easy to install, Long lasting filter
The filter system I have is great... Mounts under the sink, was easy to install. The filter are easy to change and not having to worry about keeping track of them is awesome, they are mailed to me I install them it's that easy. after a couple of years one of the caps developed a very tiny leak... was replaced at no cost right away.
Pros: Clean taste, Easy to install, Easy to change the filters, Long lasting filter
Although I like the AQ-4000 overall, replacing the cartridge is very difficult. Specifically, when pulling out the hoses, you're instructed to hold down this very small grey plastic collar that can't be more than 2 mm wide, while with your other hand you're supposed to pull out the hoses with the elbow plastic connectors. You can't use a simple pair of pliers to remove the connectors for fear of breaking them (they're plastic), and they stick in way that doesn't allow easy removal. I would much prefer a metal connector for the hoses with a locking collar to secure it.