Hey Rohan.

NEET is an entrance test for admission to all the government colleges, Private Colleges and Deemed Universities expect AIIMS and JIPMER. Hence there are comparatively many more seats under NEET than under AIIMS and JIPMER. So the chances for admission are a lot higher under NEET which can be one of the reasons to prioritise it more. AIIMS and JIPMER are the top colleges in India for MBBS but the seats are less and hence there is more competition. So you should prepare for all 3 simultaneously but you can prioritise NEET more as it has more chances for admission.

Best of luck