You must have seen many answers of this question in a very detail form but I will simply help you by comparing VIT and SRM on Overall basis like placements,faculties,Infrastructure etc. according to the current scenario i.e. in 2020.
VIT Vellore > SRM KTR > VIT Other campuses > SRM other campuses.
Which means SRM main campus is better than VIT Chennai but not as good as VIT Vellore. Hope this will help you in taking a decision. Kindly upvote.