I would say there are no better course. See for example if you go for Arts then also you will cover max to max three subject of UPSC which will not have all the info as per the syllabus of UPSC. So pursue a course which you want to learn. Don't go for the preference for the exam. If you go for a field which you are not interested in then you will fill exhausted with a little bit of study and thus the UPSC preparation will get hampered. So study any field you want to study and in parallel study the UPSC curriculum. This will not only build you a better possibility in the exam but will also play a important role in shaping your career.

To know more about the UPSC preparation tips you may visit the link below:

https://competition.careers360.com/exams/upsc-civil-services-exam

To know more about IFS visit the link below:

https://www.careers360.com/careers/indian-foreign-service-officer

I hope my answer helps. All the very best for your future endeavors!