The camaro is a "real" Muscle car only 1/3 of mustangs have a sport engine in them, Camaros are cheaper , Faster, Safer and also have a more reliable engine, The mustang also tends to have more plastic parts compared to the camaro's metal parts, Camaro's also come with a free oil change for whatever model you have, mustangs you must buy the more expensive models to receive that.
A Camaro costs less and Mustang costs a lot more, so,even if you don't have much money, you can buy one. Camaro is much more cooler than a Mustang & it doesn't have to go fast so it wastes less fuel. The Mustang has a larger possibility of crashing because the one who drives a Mustang, will definitely, drive fast.
Why get a Camaro ? Everyone has that model car , and also mustangs are good but also everyone has a mustang. Be creative and get like a infinity g 35 or Nissan 300 zx . If your into drag racing these cars are ok but not your best bet. Aim for a more light weight car with a good intake or something.