BCA

Here are a few profiles that might be suitable for you if you want to work in a legal setting:
Legal Advisory: After LLB, you can join not only corporate firms but also organizations such as NGOs, individual law firms, Banks, Think Tanks (such as Vivekananda International Foundation), etc. Please keep in mind that you need to qualify the exam of Bar Council of India before you can do any of these.
Government Sector: You can apply for government jobs in the legal departments of various PSUs as well as High Courts. Such posts are generally filled by Public Service Commissions of various states. You can also take SSC CGL exam for posts such as Income Tax Officer, Assistant in the Central Secretariat, etc.
Teaching: You can go in for LLM and then take up teaching law as a subject in law colleges.
Judiciary Exams: If you wish to take a place in the judicial machinery of the country, you can prepare for judiciary examination for the posts of Judge, and magistrate.
Higher Education: If you wish to work in a particular field such as Cyber Law, Labour Law, International Law, Intellectual Property Rights, etc., then you can pursue an added certification for it. It will help you explore your interests and also lead you to a specialised field.

You should pursue a course which you feel comfortable doing/studying, and where your interests lie. The career scope for students of IT is on the rise today. Employment opportunities that offer lucrative salaries are available to desirable candidates. The degree in B.Sc information technology serves as a very good base for students who wish to pursue their career or advanced studies in the field of information technology.
In comparison, if you pursue BCA you have a good chance of getting a job after the course, however, you will be in a lower pay grade. For better prospects, you might have to pursue an MCA. In my opinion, if computers is your strong point you should pursue BCA and if general science is your forte, pursue B.Sc. The choice is yours. Good luck!

It does not make much sense to do a BCA after you have completed a Diploma in architecture, unless you are interested in studying computer sciences and pursuing a career in the same field.
To improve your career prospects you need to study further either in your technical field or in a general area of study. If you wish to study further to improve your job prospects, then as a Diploma-holder, you can seek lateral entry to the second year of BE. Several engineering colleges offer this provision. You can pursue your Bachelors in architecture from Indian Institute of Architects (IIA) through correspondence. It conducts non-formal engineering education programs, successful completion of which is recognised as equivalent to a graduate degree in engineering. The Associate Membership of the Indian Institute of Architects (by examination) is at par with Bachelors Degree in Architecture of recognised Indian Universities as notified by the Government of India for the purpose of employment and services under Central government. In appropriate field.