Name brands IMO
are no better then the one's you can buy on the net.
Only 2 companies make the Membrane that I know of and there both good. This is the main part of the unit.
The other filters are carbon and micron...... Not too much to go wrong here.
resin... This is where you can get a different quality product, but not a major issue because you will be changing them out on a regular basis.
So I would go with what ever unit is cheaper. I have a airwaterice unit and I love it. But there are cheaper units on the net now, it seems like there are more and more places selling them every month.