There are many different brands out there and they all pretty much do the same thing. Most of them will give you clean water.
IMO, the Aqua FX units are top of the line for two reasons. 1) You get inline
TDS meters and pressure gauges standard on most of them...these are expensive options on other units if they are available at all. 2) They are made right here in the US and have an excellent tech support staff to handle any problems you might have with installation or use.
The Aqua FX units also have a full size
DI cartridge instead of the smaller inline
DI filters than many of the cheaper units come with.
Why get a larger one? Several possible reasons...the larger unit allows you to add drinking water without worrying about running out every time you use it. It gives you faster recovery time and the
RO membrane will last longer. If you decide to add more tanks, you'll have the
RO/
DI capacity to support them. While I can't speak for everyone else, the difference on my site between a 50gpd and 100gpd is only $20...not really much when you consider you are doubling you capacity.
JMHO.