I believe NIT Trichy is the best Technical Institute for MCA in Tamil Nadu having excellent faculty, infrastructure, career and placement prospects. You need to appear and ace the NIMCET Exam for a Seat in NITs for MCA.

For more information about MCA from NIT Trichy do follow the link below

https://www.careers360.com/university/national-institute-of-technology-tiruchirappalli/mca-course

There are many other Good Universities for MCA like PSG Coimbatore, VIT Vellore, SRM and Presidency Chennai. Do follow the link below for more information

https://it.careers360.com/colleges/list-of-mca-colleges-in-tamil-nadu