Let's get something clear. Pizza is important.
The only thing second to importance in pizza is the toppings that go on said pizza. And this is where most people tend to fundamentally disagree.
Here were some of the answers.
A Little Leaf Makes A Big Difference
This is how my husband orders pizza for me. Not even kidding.
"I'd like a cheese pizza with basil. Extra basil. And then when you think you have enough, reach in and clear out that container. Then head to the storage room, grab all of the basil and add it. When you're done with that, head back to the garden and pull the whole plant. Then go next door and grab any of their basil. When you're done, you're about half way there."
I love him.
Aepples And Banaenaes
Banana peppers. Oh man a thin crust pizza with italian sausage, green olives, and banana peppers is the best!!
Anchovies get a lot of reflexive "eww, gross" reactions from people who probably have never had a pizza with anchovies, but they're great.
Mushrooms, every time I say that mushrooms are my favorite toppings I get a "eww" as I reply but I don't know why. They're so good.
A Little Extra Crunch
Basil? Onions? Chicken? None of these are underrated. 99% of places will have these options. The only guy below with a real underrated one was the potato guy.
A real answer is roast corn. A lot of it too. Cheese, a little onion and pepper and a crap ton of corn.
Spicy But Less Greasy
Salami. The flavor isn't as strong as pepperoni, but still definitely there. More importantly it doesn't curl up and get burnt on the edge with a pool of grease in the middle.
All Parts Of The Cow
I dunno about underrated exactly, but green chili is an excellent topping that's hard to find outside parts of the southwest. Potato is definitely underrated, although tater tots specifically are meh. Most underrated, in my opinion, is cow tongue, which is amazing on a pizza.
Pineapple, apparently. I'm sad for those of you who have never had a good Hawaiian pizza.
For those of us who have... spinach! Saw it on the Pizza Hut web app and decided to try it. I used that, olives, red peppers, and meatballs with the Balsamic drizzle. Called it Pizza Caprese and it was amazing! Got weird looks when I picked it up, but the second time, I told then they should try it sometime.
A Little Bit Of Pasta
Toppers Pizza has a macaroni pizza that's the best damn thing you'll ever have. Especially if you get the buffalo chicken mac and cheese tall boy. Truly superb.
Also, Kwik Trip has surprisingly good food. Their mac pizza is pretty good, just add hot sauce. They also have a bacon mac pizza but it's harder to find.
More Kinds Of Spicy
Sausage. Not that people don't like sausage on pizza, but in Massachusetts out by Cape Cod, where there's a huge Portuguese community, a favored topping for pizzas (not to mention filling for omelets) is chourico, and its less-spicy cousin, linguicia. I don't doubt there're a lot of other local toppings the general public doesn't know about.