I have a 3 moa and a 6 moa on different pistols. With me it depends on how far I intend on shooting the pistol and at what size target. At 400m the 3 moa it perfect for a 3 foot gong. At 100m the 6moa is almost hiding a 10" square in daylight on full brightness with the amount of shake I introduce to the pistol.
Try as many red dots as you can as for some this is quite the monetary investment.