Both are android box. Both by biggest DTH providers of India. One is upgraded version of older internet TV box(Airtel). Other is second chance of providing time shift tv (Tata Sky). Which one is better than other ? Lets compare one by one. From hardware to Remote to subscription to features.
Airtel Xstream+
Tata Sky Binge+
Processor
Broadcom BCM72604 B Dual-core 1.8 GHz
Broadcom BCM72604 B Dual-core 1.8 GHz (ARM Cortex-A15) processor
Hope every relevant point was covered. If there are not elderly in the house then I would recommend Fire Tv or Mi tv instead as both are faster in reboot and easier to use with slick interface.