Among these two, I will definitely recommend you SRM university if you are getting main campus only, then it will be worthable!
KIIT University is also good, but not better than SRM UNIVERSITY. According to this year NIRF ranking, SRM UNIVERSITY is in top 40 colleges in India.
Fees are approx same between those colleges. But one thing about SRM is very bad, their hostel life! It is very difficult to survive their, to many restrictions & SRM university management are worst! But along with KIT UNIVERSITY, it provides luxurious campus & hostel life to students. & infrastructure is also good.
I will recommend you to get CSE, because none of core companies visited in the universities. So, I think mechanical will not be worthable. Just minimum of core company just visit their & take just 5%-10% students, otherwise rest is IT sector..
So think before go!
Both are a good private institution in India and reputations are similar.in terms of placement record, SRM is far better than KIIT but KIIIT also a good placement record.
if you get mechanical in SRM then prefer it first otherwise KIIT also a good option.