After doing some research online, I would say that all the courses at ISI Kolkata are amazing if you know which field you have to choose. Everything depends on your choice of the field as every field is distinct from one another.
Now, I would mention that for M.Tech CS & QROR, these are already well-established Programs and need no introduction.
QROR:
CS:
Crypto:
I hope this helps you in clearing how all the three courses are distinct from each other. Each has its different criteria and comfort.