If you are interested in ISRO, you should consider IIST Trivandrum as your best option. More than 60% of each Aeronautical/Avionics/Electronics batch are directly inducted into ISRO provided you have grades above 7.5 and clear an interview.

IIST Trivandrum is one of the Top Technical Institutes in South India after IISc Bangalore, IIT Madras and IIT Hyderabad with excellent infrastructure,faculty and research facilities.

For more information about admission procedure and cutoffs of IIST Trivandrum are as follows

https://www.careers360.com/university/indian-institute-of-space-science-and-technology-thiruvananthapuram