I would try thirschfield's wonderful meatball recipe. They are a bit unconventional, but insanely delicious. I made them and they were worth every calorie and penny! Make these for a crowd because once you try one, you will want to eat the entire batch.
http://www.food52.com/recipes/6267_meatballs_emiliaromagna_with_pasta_sheets

The best meatballs I have made are from A16 restaurant in San Francisco--insanely good. The recipe is in this article:
http://articles.sfgate.com/2005-02-09/food/17360132_1_meatballs-home-cooked-taste-comfort-food

I also love Rocco's Mama's meatballs, they are much simpler than the above and they are moist with good flavor:
http://www.roccodispirito.com/recipes/mama_smeatballs