I got 86.6 percent in 12th cbse.which govt university and which is the bestcourse I should do.?
I would suggest you apply for colleges under Delhi University. As you have not mentioned your caste so I am providing you the link to the 10th cutoff of DU from 2018. You can finalize your course according to that.
2018 DU 10th cutoff list: http://www.du.ac.in/du/uploads/Admissions/Cut-off/2018/10th%20Cut-Off%20-%20Science.pdf
Your board score is pretty good . If you want to do graduation BSC, BA then you can take admission in BHU and Allahabad University . These are the good government college. Or if you have interest on engineering then you must qualify Jee Advance and get admission in IIT .
Choose course by yourself accordingly your goal and interest .
Thanks and regards
Dear Aspirant,
in terms of best course it depends on your interset, for what you have most interst you can choose the field related to it and college as per selected course.
All The Best!