My mom's is what I use:
Equal parts ground pork and beef (one pound each).
Start by cooking chopped onions and chopped green peppers (with salt and pepper), in enough water to cover them, till there's little water left and peppers change color somewhat. Drain (reserve drained water to add to the sauce later).
Dampen a half loaf of white bread with milk or water. Mix in three eggs. Mix in cooked peppers and onions, along with salt and pepper. Mix in ground meats thoroughly, till everything is evenly mixed.
Make a loaf shape with a groove down the middle, lengthwise, to assist center cooking.
In the oven at 400 for a half hour. Take out and wrap with bacon, then back in the oven for another half hour, or until cooked all the way through.
Sauce is simple: Straight tomato sauce from a can or box (not pasta sauce) to which you've added the reduced water from cooking the onions and pepper, and the drippings from the meatloaf, along with the cooked bacon from the meatloaf (after meatloaf is fully cooked and resting), then season with salt and pepper to taste. Simmer and reduce while the meatloaf is resting for ten minutes or so.
Slice and serve with sauce and mashed potatoes.