Both vit and SSN are reputed and famous colleges among enginnering enthusiast. It is hard to compare these two on basis of placements as both provide good percentage of placements into famous corporates.
However going by the ranking vit outdo ssn. Although education provided by both the colleges is good. Vit slightly do better in the placement sector, it provide better student exposure and programmes to tone up their skills.
I will suggest you to read reviews for both the colleges directly from students to get a more authentic view point.
Vit chennai :- https://www.careers360.com/colleges/vit-university-chennai
Ssn :- https://www.careers360.com/colleges/sri-sivasubramaniya-nadar-college-of-engineering-kalavakkam
Hope you find it helpful.