Dependa on the region. Personally I love me some chicken Chettinad, Kerela prawn curry, appam and idiyappam.
Idli and Appam, actually South Indian food is way more vast than the popular south Indian that we know. There's a lot of variety.
It's a veryyy broad genre you are talking about. But I would probably have Chicken Chettinad with Malabar Paratha when given an option.