I'm a pizza fanatic, and sadly none of the pizzas within the DLR area have wowed me. I've had Naples and it was OK, my major gripe was the wait. It took forever for them to get our food -- it may have been an off day though. I haven't been to Splitsville, but have heard some not so great things about their food. People say its way overpriced, but you are right that they have a better variety of foods if that is a key factor.
Another option may be the quick service White Water Snacks in the GCH. They just added larger artisinal pizzas to their menu that look pretty decent. The pizzas are also offered at Storyteller's (also at GCH) for lunch and dinner, which is a sit down restaurant. At dinner they also have a buffet option if that appeals to some in your party, but you can still order regular items off the menu too. (ETA: If you see pictures of Storytellers with the characters, please note that they only come out for the character breakfast. They are not present for lunch and dinner).
I've heard that Marri's pizza is a good option for hotel delivery. I personally haven't tried this, but have heard many good reviews here on the disboards.
