You are very correct that IIT Bhu has a strong alumni network aincs it is very old.

On the contrary IIT Hyderabad is relatively new , but the placement have been very good in the previous year as compared to IIT Bhu. IIT Hyderabad being new has new and updated infrastructure and hostel facility but IIT Bhu has old infrastructure which are renovated. IIT Hyderabad is rising through ranks in the years and it will attain new heights in the years to come.

So if you consider my opinion then you should definitely go to iit Hyderabad.

Good luck!