Should homemade lasagna be frozen cooked or uncooked?
I'd say freeze nearly all of them uncooked and bake when ready.  That way they go through only one cooking and maintain the fresh lasagna taste/feel.

The sauce and and the cheese will freeze ok.  Mozzarella is a pretty sensitive cheese and once it's been baked, it's not going to hold as well when thawed and re-warmed. In my experience it gets gummy and the fat runs off.  You have much better chance of enjoying a good meal with the cheese frozen raw.

Unfortunately, your noodles will likely take the hardest hit, but will likely fare better than going through two heat cycles.

The ground beef and sausage will also fare better that way.

The reason I suggested freezing MOST and not all, is that there are times when you're behind the 8-ball, hungry, and don't have the time to bake the sucker, and even ponder settling for dog-food.  At that point having a silver bullet in the freezer is a bonus ;) and you'll be ok with inferior lasagna.