unless your going all out and want something with De-Ionisation (DI) and all stainless steel,they are all pretty much the same,the RI membranes are only made by a few manufactures regardless of what the sticker on it says,and only 3 or 4 of them are the most common,the GPD rating is what it should produce theoretically but temp,pressure and TDS on the input water will make differences,in highgate my TDS from the well is 400+,with the unit i use(and the ones im selling currently) bring that down to about 3,the DI will remove or polish out whats left,i dont use one myself(or feel the need) but they can be added very easily,your in chatham,go talk with elite water by walmart,not the boob close to the critter shack,the ones you buy for home drinking use will serve a dual purpose for you,larger storage tanks are cheap at TSC.