Thanks for the A2A.
I am not an expert on law schools, but from my knowledge of other courses I will recommend KIIT as its the more reputed, older and generally-better-in-almost-all-terms institution except hostels(which are manageable but the ones at UPES are better).
Also, let me jot down a few factors you may want to consider in your decision making.
My analogy for students at UPES law(basis interactions with total 5 students at a national level debate and 3 more at a Model United Nations) would be something like Amity. More fashionable, definitely richer and a little arrogant; none of this is meant to be an offence to anyone, I find myself a little arrogant as well! KIIT people have been more affable during similar interactions and definitely more humble than their UPES counterparts.
Another critical thing that affects your decision can be the proximity to your home and the connectivity between the college and home. In case its your first time away, staying a little closer to home can be better.