In WBJEE 10200 what college is best for me? I'm thinking about RCCIIT or techno saltlake...

First of all, congratulations for your marks.
As your rank is good, you can easily get seat into Techno India Saltlake, or RCC Institute of Information Technology.
But in RCC Institute of Information Technology, there is no civil or mechanical branch. Though I don't know which branch you are going to choose.
But both are very good private college , that provide quality education and placement. Moreover, RCC Institute of Information Technology is government aided college, though the college fees is same as other private colleges.
Now its totally upto you.
Good luck...