Ask any Hyderabadi, and he will tell you that his Biryani is BAE. Ask a layman on the streets of Chennai, and he'll swear by Dindugul Biryani, or say Ambur Biryani is the original Biryani. Travel to Kerala, and the 'chetta' will offer you the ancient 'Kuzhi Mandhi' on a plate and tell you this alone is the one true Biryani! 
So here's everything you need to know about the Biryanis of the South.