Here are my ratings for the IIMs

• IIM Ahmedabad Bangalore Calcutta: 10
• IIM Lucknow: 9
• IIM Kozhikode and Indore: 7.9
• Other second-generation IIMs: 7.6
• New third generation IIMs: 6.8

The above rankings have been done on the basis of age, placements, and research. I don’t think these factors are enough to rank IIMs.

Another major parameter of comparison is the duration of the establishment. 

• First generation: (est before 1984) Ahmedabad Bangalore Calcutta Lucknow 
• Second generation: (est. before 2000) Indore and Kozhikode 
• Third generation:  (est. around 2009) - Ranchi, Raipur, Rohtak, Trichy, Udaipur, Kashipur, Shillong
• Fourth Generation: New IIMs (after 2014) - 7 IIMs

Most of the FT rankings and online rankings are based on this parameter. In reality, every IIM has top-notch faculty, infrastructure and placements m. Yet the new IIMs will take some time to reach the top.