Which college is better for an MBA (PGDM) in marketing among IMT Ghaziabad and baby IIMs (Nagpur, Visakhapatnam, Amritsar)?

It all depends on what you are looking for, your goals, and your preferences. IMT Ghaziabad (Estd. 1980) is an old legacy institute while the baby IIMs (Estd. 2015) (although it is offensive to call them that) are relatively new. Below is a table comparing their absolute numbers like Fees, Highest salary package, and the average salary package.

As you can see there is not much difference in the colleges in absolute numbers the only difference is the IIM tag.