B. Tech in CSE is better than Bsc in cs or mechanical . To do  B. Tech in Computer Science you must have done 12th in Non. Medical stream (PCM) with 60% . Various engineering colleges in India also offer direct admission on the basis of score in 12th .Various engineering colleges in India also offer direct admission to diploma holders in second year of the course and in reputed institutes ,after completing diploma student gets entry in second year of B. Tech through LEET. Some private institutes like BITS Pilani, VIT , LPU University etc conduct their separate entrance test. Top colleges/ universities are: DTU, BITS 
College of Engineering Pune
Lovely Professional University
Hindustan Institute of Engineering Technology Chennai,
Vellore Institute of Technology
P.S.G. College of Technology Coimbatore
Madras Institute of Technology Chennai,
SCMS School of Engineering and Technology Cochin
Veermata Jijabai Technological Institute Mumbai
Anna UniversityCollege of Engineering Pune,
Jadavpur University

Dear friend ,


I will prefer you to take B.Tech in mechanical engineering due to following reasons:


B.Tech will give you more salary in any firm or company. B.Sc person will get comparatively lower salary.
You have more carrier options available after B.Tech. The options after B.Sc are limited.
You have an opportunity of foreign placements through B.Tech while simple B.Sc will not get you a foreign call.



Hope this helps you ...
Good luck !!!