I'm in 2nd year btech which is competitive exam is better to start preparation RRB or SSC CGL ?

Hello,

Preparation for any government exam is more dependent on your areas of interest especially pertaining to job profiles, and to a some extent the syllabus also matters, for instance if by RRB you meant Railway Recruitment Board then it does recruit on the basis of btech degree for JE post, other than this there are also posts based on the eligibility of graduation in any stream from a recognized university which is common posts in the sense any graduate can apply, however if you meant IBPS RRB then it does recruitment of office assistant and officers, it's pattern and syllabus is like any banking exam, speed and precision is very important in qualifying banking exam, also the level of banking exams are comparatively higher than that of SSC CGL, both the exams offer good posts as you must  be aware that competition has changed drastically and it has increased a lot in the recent times, also the fact that many engineering graduates are qualifying both banking exams as well SSC CGL and also UPSC or state civil service exams, so you can take this as an example that you're also capable of qualifying the same, but then you have to analyze which job profile you find interesting, in ssc cgl there are field jobs as well as desk jobs, while in banking it's  got more to do with dealing people, their queries, and taking care of other things as per instructions provided by higher authority.