Do not rush to buy anything. Keep the bribery packed dealers out. But buy for next 30 years. Until then the existing air defense systems are good. They have to shoot Pakistani planes which the existing systems can handle. Chinese will always theaten in the mountains of Tawang or Ladakh but stay out of a shooting context, because their modern planes would fly from far away bases (none in the neigbourhood to fly high performance planes from 7,000 ft) with tired pilots and easy prey to the Indian Airforce before they meet the local air defense system.