How good are IIIT Bangalore and Allahabad compared to IIIT Hyderabad?

When it comes to IIITs, IIIT Hyderabad is by far the BEST. IIIT Bangalore is good as well and has some good faculty, but it doesn't have the fire brand in CS that IIIT Hyderabad does. If you're looking for an advantage, IIIT B is located in Bangalore, but then again, IIIT H is located in Hyderabad, so it's not as good as IIIT H.

IIIT D and IIIT A are both government-run and have a 50% reservation. This puts them behind the above mentioned colleges. IIIT D has better faculty and is located in Delhi, which gives it a certain location advantage. However, IIIT A is an older institute. Both places are filled with Delhiwalas and UP bhai log, which doesn't help them either.

If you're a North Indian, you might like IIIT A/D more than IIIT B, and vice versa. However, almost all Indians like Hyderabad as a city. The majority of people in Hyderabad are friendly and know Hindi, so North Indians find it easier to adjust. At the same time, Hyderabad people are not language chauvinists like other South Indians (read Tamilians and Kannadigas), so that also helps. Plus, if you're a South Indian, you will easily adjust to Hyderabad since it still has a Southern Vibe to it.

In short, IIIT H is the best among the above depending on faculty/location/college life and the general atmosphere. If you're not getting IIIT H, you could try for the Top NITs (only Trichy, Warangal, and Surathkal) and then your famous state colleges like NSIT/DTU for Delhiites, Anna for Tamilians, Jadavpur for Bengalis, COEP for Marathis, etc., JNTU, etc.