I like juicy hamburgers which have at least an 80-20% ratio of lean to fat and a 70-30% ratio is even more tasty for me. Not the healthiest chow for sure, but I don't eat it every day.
Store bought ground beef labeled '80-20' is usually ground chuck, since most cuts from the chuck primal have about 20% fat naturally, but it's rather one-dimensional in flavor, I think.
For homemade ground beef, I grind a blend of chuck, short rib, & brisket meat for a more balanced flavor.
Ground sirloin has great beef flavor, but is much leaner than 80-20, so I would add fat to it if grinding or mix it with another meat. Same for bison meat -- great flavor, but very lean (and very healthy!).
