It’s not easy to decide which one is the best, but five low acid coffee brands are the most popular (and can be conveniently bought online): You may look at

These are the good tasting fruity acids that we all love in our cup of coffee. Overall brazilian and el salvadorian coffees are probably the lowest on the acidity chart

Isagenix offers an organic coffee that is tested for mycotoxins and roasted to maximize flavor. The issue with coffee is that the caffeine in the coffee combined with the acidity