I feel like not enough people have given feta a try. Maybe because it's usually a premium topping and you have to pay a little extra for it, or maybe because it just looks gross. I usually only get it when I'm stealing food from work. But damn does grilled chicken, feta, tomato, and onion make a tasty pie.
Egg, if you're non-vegan.
If vegan, just go basically shrek mode. Garlic in Oil, Onions, Capers, Olives. Add shitton of rocket after baking, drizzle with balsamico vinegar.