What antacid is best for neutralizing stomach acid?

They are all the same potency for the same amount of calcium carbonate in a tablet as stated on the label.

You may have different preferences with regard to the available flavors on each brand. The labels will also show different inactive ingredients such as sweeteners (sugar, dextrose or sucralose) and different food coloring ingredients. If it has dextrose, it may also contain a tiny amount of gluten. Some people may claim to be allergic to some food colorings.