Brown beef in a large pot or Dutch oven over medium-high 8-10 minutes, breaking up with a wooden spoon, until no pink remains; drain excess fat.
Cook onion and pepper 5-6 minutes until softened.
Add garlic; cook 1 minute until fragrant.
Add chili powder, cumin, paprika, oregano, and cayenne; stir to coat meat and vegetables and toast 1-2 minutes.
Stir in tomatoes, tomato paste, broth, kidney beans, and pinto beans.
Add sugar, salt, and black pepper; bring to a boil.
Reduce heat to low; simmer uncovered 1 hour, stirring occasionally, until thickened.
Adjust seasoning to taste; simmer another 15-30 minutes for thicker chili.
Serve hot topped with cheddar, sour cream, and green onions, with cornbread.