My friend studies at IIIT Allahabad. He considers it better than most of the IITs out there. If you are not after the IIT tag, go for IIIT Allahabad. However, both these institutions have an equally great reputation as eminent institutes of India.
You may want to consider the following points as well, before deciding.
Moreover, a lot of new departments are being constructed as BH5 7 floors building. The institute will rise in the years to come according to the plan charted by MHRD which includes the addition of startups, MOOCs, and employment of faculty members from countries abroad.