B.Tech as you know well is a 4 year course. Polytechnic will be 3 year course only. After polytechnic if you want to do B.tech you'll be admitted directly to the 2nd year in most colleges.
So for a polytechnic person to be equivalent to his B.tech counterpart, one will need 3 years of polytechnic+ 3 years of B.tech.
What you can achieve in 4 years of B.tech will take 6 years through polytechnic. Also anywhere you'll go, an engineer will be senior to a diploma holder (polytechnic).
But in the end its completely up to you, so I suggest you take a more in depth look into both these courses, and then finally decide for yourself.
Feel free to ask if you have any more queries.
Hope this helps!
All the best!
Candidates can check B.Tech Cut off for Top IITs & NITs here.
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