I am a graduate of amity affiliated to the GGSIPU University.
I have seen the infrastructure of Amity law school affiliated to amity university and I can assure you that if they convert the law school to a starred hotel, you wouldn't get to know the difference.
I have also been to the symbi noida campus and the same is equally impressive and gives a collegial feel.
From what I have seen and learned, i think both the colleges are equally good or bad in any which way you look at it.
I would look at some other factors such as where you will stay during the five years. Amity noida, is closure to the hip and happening area of noida. (at some distance, but still closure than what symbi is)
if you are getting hostel facility at both places, then the confusion remains. but if at one place you are getting hostel and at the other place you have to manage with paying guest, I would suggest you take the one with the hostel.
One more suggestion is, assuming you have graduated this year itself. I would recommend you take admission and prepare for the CLAT again. it is still better to get into a National, than these schools.
irrespective of what one may say, you would require a mentor to help you your initial stages of life as a lawyer. so if you dont have an uncle to help you out professionally, seek the national law schools.