Updated: Oct 3, 2020
Purified water is best for coffee makers from a coffee taste perspective. Ideal TDS value of water for this purpose is between 75 - 250.
Distilled water has a near zero TDS value. It is completely devoid of minerals & bicarbonates, which make it great for use in a car battery but the lack of minerals & bicarbonates causes it to impart a flat taste to coffee. RO water has the same low TDS issue.
In addition, distilled water can also speed up corrosion of internals in some coffee makers, compared to simple filtered water.
Due to these reasons, almost all coffee maker manufacturers recommend using filtered water for their coffee makers and some even specifically discourage the use of distilled water. Here’s a screenshot of a Kuerig coffee maker user manual:
The Specialty Coffee Association of America recommends following range of water characteristics for brewing specialty coffee: