It's best to avoid buying packaged ground meat as although the labelling will tell you the fat content, you have no way of knowing whether it comes from low or good quality meat; as meat is ground and packaged together, one packet may contain beef coming from dozens of aged dairy cows rather than cows bred for their meat. Always use meat with a bit of fat as opposed to lean meat, as it will dry up otherwise when cooking.
You need meat that has a fair bit of fat on it, at least 15 to 20%, to get the most flavour. To make burgers, use chuck roast or marbled sirloin steak for beef burgers, alternatively use pork or lamb shoulder.
Meatballs and Meatloaf
For dishes where you're going to mould the meat into balls for instance, or combine with sauces, use chuck roast, chuck steak or skirt steak if you're using beef. For pork dishes use pork butt or shoulder, for chicken use the breast (remembering to skin and remove bones, of course).
Once upon a time any leftover meat would go into making sausages, however some good cuts for sausage-making include pork shoulder or Boston butts for pork sausages, and for beef sausages the best are chuck roast, chuck steak, shoulder, pot roast and blade cut roast. You can also make veal sausages by grinding any cut of veal, or venison sausages by using the shoulder.
If you want to use minced meat in sauces or as an ingredient in spaghetti Bolognese for instance, chuck steak and shoulder are the best cuts for beef mince as they will impart a good flavour. Use the breast of the chicken, pork butt or shoulder, or veal shoulder (boneless).