I've eaten at the majority of downtown recommendations and GiOio's tops them all! I live a few blocks from D'Agostino's and I wouldn't consider ordering from them.
http://www.gioios.com/menu.htm
Best value is 2 medium pizzas & a 2 liter soda for around $12. For meat eaters, I highly recommend the pepperoni or the Italian sausage.
Located around Clark & Wrightwood