Buying a RO/Di unit - Help

[Fragzilla]

Originally Posted by trilinearmipmap

IMO these units are pretty generic, sharing the same design, basically the same fittings, and the membrane and filter inserts are generic too. I would buy based on cost and the features you want eg. an auto flush kit, float valve kit, pressure meter etc.

not knowing anything about these units other than they clean you water. What options are worth while and the options that are a waste?