Well, I would say, the best water filter will have the following characteristic :-

1. Filter Cartridges as we know must be replaced periodically. So filter replacement must be the cheapest.

2. Filtered water must be the cleanest.

3. Must have some form of water filtration standard in producing water. Well, you must imagine water filtration using water with LOW and HIGH incoming pressure, the filtered water must be the same.

With the above criteria in mind, it narrows down to :-

Reverse Osmosis or Distilled Water.

Don't listen to people telling you that we cannot drink water that is too pure. this is marketing gimmick as Reverse Osmosis water filtration is what they fear most. There is no science that says mineral cannot be added to pure water which will give you mineral water.

All water filters including AMWAY fails point 3 above. People always say we need to drink mineral water, but try asking them these Questions:-

1. Can they guarantee the mineral content of their water filter.
2. Can they guarantee water produced through their water filter say from Johor, or from Perlis or any other place have the same mineral content. So what mineral are they talking about?
3. Don't forget all Mineral water that we bought from super market do label their mineral content on the label.
4. We can equate toxic chemical as water mineral that their water filter cannot get rid off, that is why they have to sing mineral water.
5. A higher incoming water pressure will always produce faster than a lower water pressure. Therefore water quality will also be different. No water quality standard.

Reverse Osmosis on the other hand.

1. Water produce has no mineral content, but mineral can be added after filtration with mineral stones.
2. There is a standard model like: 50Gallon/day, 75Gallon/day and so on. This rating is set by the manufacturer.
3. Whether Low/High water pressure, output water still the same.
4. Can be used to filter sea water. This is what used onboard ship.
5. Water even sold in Supermarket.

Mineral water sold in supermarket do label their mineral content.

Like iron, calcium, and so on with content level.

This mineral water filter cannot even tell us the mineral content and level after their water filter, what is that to argue about we must drink mineral water.