Either would be fine. I have delt with BRS with good results and have known Marc, (melev), for a few years. Both will work well with the after purchase things also. You want a good TDS meter also. Another good thing to know is the pressure of your incomming water supply. I also take for granted you have a city water supply. If you use a well speak to either as this may make a change to what you need.
Make sure what ever you get has a vertical DI cartridge as they will not channel water.
I got a water general off of ebay and probably saved $40, but wish I would have bought a better one right away. I ended up spending more money updating it to a vertical di and pressure gauge etc. The ones from melev and BRS will all have the John Guest push fittings instead of screw on fittings for the hose connections.