Hello,

If your focus is only directed towards appearing for UPSC exam, then it's best you go ahead with humanities stream, so you can choose subjects as per your preference, for example with UPSC it helps if you do your graduation in subjects like political science, public administration, history, geography, economics, even law  is great choice, as there  is overlap of general studies with optional papers as well, however I would like to emphasis if you're not sure and you want to go for back up plans such  as medical, commerce, engineering etc you can go ahead with option also, in upsc people from diverse backgrounds  qualify this exam, so let's say you're not sure, and you're an engineering aspirant, you can go ahead with BTech, and also earn few years of experience if you want to explore your domain further and after that also you can appear for UPSC, there are candidates who have had relevant years of work experiences and then appeared for UPSC, so the choice differs from person to person, and one thing remember that no matter which stream you choose in 11th or graduation, you'll be eligible to appear for UPSC as there is no set criteria of belonging to specific stream, but yes the subject combinations at 10+2 and graduation of humanities do help to a  large extent.