Spicejet has had a ton of bad luck, first with the Marans and then with Covid and has still survived. I am fairly confident that under Ajay Singh whenever the airline catches even a small break, it will capitalize on it completely. Indigo is running mostly because its scale has given it an impressive moat but as soon as a viable options comes along, it will face a lot of pressure.
Disclaimer: Invested in both Indigo AND Spicejet. Aviation as a theme for growth is solid in India.