For traditional recipes that call for paprika, it's best to use what the recipe calls for, as the paprika is there for a reason, and its flavor and color are intended to give the dish an overall flavor profile and aspect that substitutions can't add.
VARIATIONS

Capsicum Extract: Nature’s Potent Remedy
FAQ: Is crushed red pepper the same as chili flakes? And are chili flakes the same as red pepper flakes?
Paprika & Chili Products: A World of Flavors
However, its spiciness and heat level make it an excellent substitute for paprika powder. It's available in mild, moderately hot, and hot varieties, so you can easily replace any hot paprika variety in your recipe.

Despite its misleading name, sweet paprika, of which Hungarian paprika is one variety, isn't sugary or sweet at all. Instead, it's called sweet paprika to distinguish it from other types of paprika that are spicy. The end zing, or lack thereof, depends on what type of peppers were used to make the spice. Some paprika is made from red bell peppers, while other paprika is made from chili peppers. If you don't have sweet paprika on hand, you can use any number of substitutes, many of which will yield flavorful results.
If you can’t find fresh red chillies, just use the good old dried red chillies. Soak the dried chillies in warm water to rehydrate them and then grind them up. When your sauce is ready, you should see tiny pieces of chilli and minced garlic floating around. These little bits are the life of the sauce.
Paprika and Bell Pepper
This is my shortcut for salt-preserved chilies. I’m not really sure if it actually approximates salt-preserved chilies, but it does add really great spice and texture! Set aside and prepare the rest of your ingredients.

