Heat large skillet over medium-high heat. Add ground beef and diced onion. Cook 7-8 minutes, breaking meat apart, until browned.
Add minced garlic and diced bell pepper to skillet. Cook 2-3 minutes until fragrant.
Drain excess fat from meat mixture. Transfer to slow cooker.
Add crushed tomatoes, tomato sauce, diced tomatoes, and tomato paste to slow cooker.
Add all drained and rinsed beans. Pour in beef broth.
Add chili powder, cumin, paprika, oregano, cayenne, salt, pepper, and brown sugar.
Stir all ingredients thoroughly until well combined.
Cover and cook on LOW for 6-8 hours or HIGH for 4-5 hours.
Stir occasionally if possible during cooking.
Taste and adjust seasonings 30 minutes before serving.
Serve hot with desired toppings.