In a large mixing bowl, mash 1 of the chopped avocados with a fork. Add the remaining chopped avocados, the garlic, tomatoes, lime juice, lemon juice, green onions, basil, crushed red pepper flakes, salt and pepper; stir to combine. Taste and adjust the seasoning, as needed, with crushed red pepper flakes, salt and pepper, to taste.
If not serving immediately, sprinkle a bit of lemon juice over the top and cover put plastic wrap directly on top of the guacamole surface. Store in the refrigerator for up to 2 days.