Man, a one topping pizza is just pointless. You need to have a combination of flavours in there. I grew up with "supreme" pizzas, so I appreciate the melange (and yes, that includes olives and onions along with a couple of meats). If I'm just ordering to have pizza around the home (which is surprisingly infrequent) I'll go with a small Pep/onion/jalapeno, and a Sau/onion/shroom. I also enjoy experimenting with whatever combinations a place might specialize in, which might be pretty oddball.
And I like mozzarella as much as the next guy, but cheese isn't a topping. It's an important part of the base of a pizza, but it shouldn't be the primary thing.