There isn't anything as such best course for UPSC, as its eligibility criteria is passed graduation in any from a recognized University, you need to be 21 years old and can apply even in the final year, there's no doubt that UPSC tends to be more humanities oriented, those from arts backgrounds are already well acquainted with the subjects, but people from diverse streams crack this exam such as Medical, Engineering, Science etc. So, eventually it's your preparation and dedication that matters, it's also good to have a back up plan regarding this as UOSC tends to be more unpredictable, eventually what matters is your choice, in case you have other aspirations such as pursuing medical, technical or any other career, you can do so,earn few years of experience and later on apply for UPSC, many aspirants follow this path as well.
For becoming an IPS you have to give UPSC exams, for clearing this tough paper you should do that course which have similar subjects with the syllabus of UPSC.
BA is one the best degree you can have which will help you for preparing for civil services from your college.
You should go for that.