After a BTech, will an MBA be a better option?

It depends purely on the perspective of an individual , many people who want to take their career towards management take up the option of pursuing MBA ,but MBA from only reputed institute will help in my view.And its advisable to get some work experience atleast 2-3 years before thinking of pursuing MBA.

But if someone is very much technical oriented its better to take up a job first , gain some on the job experience and then take probabaly pursue M.Tech in relevant specilization. 

Not necessary that MBA would be a better option. You have to make your choice of profession you want to be after your studies. Being a MBA professor i feel, students doing MTech after BTech can pursue a profession in teaching as well as in research, there are plenty of engineering institutes where you can make your career and prosper.

Students doing MBA after BTech firstly divert onself from their basic studies, and find it difficult with subjects like finance, as it is a technical subject they have never studied. And outcome is they choose Marketing or HR or Operations. Whereby again, the corporate industry which are related to their core studies i.e. B-Tech are the ones who prefer them over other industrial segments. 

After doing B.Tech, there are a couple of options:

Getting a job:

To get a job, the most important skills you'll need is to crack the coding interview. Learning Data Structures, Algorithms, and coding these solutions in prompt timing are invaluable to have and perhaps the most important skills in landing your dream job. The better you are at these, the better the prospects of having a high paying job

Higher studies in India (M.Tech, PhD)

If you are more academically aligned and you think research or teaching is something you'd end up doing, these lines maybe better for you. GATE can help you get a government job as well.

Higher studies abroad (MS)

This is a lucrative opportunity as well if you're more ambitious and have a 15-20 Lakhs to invest in higher studies in US/Canada. The upside is that if you'll be able to recover most of the amount if you are able to land a reasonable job after your 2 years of studying there. This option is great for people who want to have a go at a chance to settle abroad, and to improve their credentials furhter.

MBA

For those more business inclined, and if you want to see yourself becoming an entrepreneur, MBA is an invaluable skill to have. But don't it for just the sake of doing an MBA, if you see yourself being in managerial positions, and if you want to learn business skills and soft skills, then it migth be worth preparing for CAT.