See the number of colleges offering MCA are too many. It depends upon where you wish to pursue. Most of the institute have some or the other entrance exams to get through. I also believe that pursuing an MCA from a reputed college like an NIT, or university like VIT would be advantageous than an obscure college which simply takes admissions on the basis of BCA. Also number of seats are not exceptionally high at any place simply because regulations of AICTE dont allow for things like that. Try NIMCET for the NITs. It will be great place to start. VITMEE is for VIT. 

I suggest you get back with the area you are residing in so we get better information pertaining to the state and colleges nearby.

If you are targeting NITs for MCA programme then you need to appear for NIMCET entrance exam, to apply it you should have a minimum of 60% marks or 6.5 CGPA score in aggregate of all subjects as a General or OBC Candidate. To check the complete information you can go through with the given below link.

NIMCET 2018

The other colleges you can prefer:

KIIT School of Computer Applications, Bhubneshwar- KIITEE  entrance exam

Amity University

New Horizon College of Engineering, Bangalore

To apply you should have minimum 50 % in your Graduation.

If you are interested for any particular state or college then let me know.

Good Luck!