I like 10% beef fat as it holds the patties together much better. My favorite recipe for burgers: 1 package Lipton Onion Soup mix(dry), 2 tbsp A-1, 1 tbsp Worcestershire, 1 tbsp Pickapeppa, 1 tbsp Tony's cajun seasoning. I get quite a few comments on burgers with that recipe.
If you are still having trouble with the patties coming apart, you can add either an egg or bread/cracker crumbs.
