Place the beef, garlic powder, onion powder, Worcestershire sauce, pepper and 1 teaspoon salt in a bowl and using your hands mix to thoroughly combine. Divide the meat into 6 pieces and form into 1/4-1/2 inch thick patties.
Heat a large sauté pan over medium heat and cook the burgers for 3 minutes on each side or until medium rare. Top with cheese and cook another minute or until cheese melts.
While burgers are cooking, cut the avocados in half, remove the pit and scoop the flesh into a bowl. Squeeze in the juice of a lime, 1/2 teaspoon salt and cilantro and mash until a few pieces of avocado remain.
Place a slice of tomato on the buns, top with cheese burgers, a large spoonful of guacamole and top with remaining bun.