One should take these rankings with a pinch of salt. These are based on surveys, and the opinions of people change every year based on various factors.
Anyway, what makes you so sure that other IITs are better than IIT Delhi? I would love to know the secret that I missed.
I like to blog about various topics ranging from education in IITs to social issues in India and US. All opinions and views presented here are my own and not of my employer.