hi,

see upsc civil service exam is one of the toughest exam in india. now see as per the eligibility criteria candidates from any of the course of bachelors degree are eligible to appear in civil service exam. so it does not matter whether you go for engineering or general degree course. however you must know that a bsc or b.s or b.com (//b.com) degree takes 3 years and btech/ engineering course is of 4 years , also btech course is much tougher than bsc or other general science courses. so if your sole target is IAS then you may take bsc , also for preparation of IAS it almost takes one year to strongly build your conceptions and practice of questions.

hope you may understand.