Hey there!!

In my opinion bitsat hyderabad is better in comparison to vit vellore as vit is more expensive , plus tha faculty in bits are good,plus it offers highest packages from all branches. Since both are good colleges but in compare among these two you definitely go with option BITS. If you didn't able to get mechanical branch in BITS then only you should go with option VIT. 

To know more about the comparison of bitsat hyderabad and vit vellore you can check out the link given below:

https://www.careers360.com/compare-bits-pilani-hyderabad-vs-vit-vellore

Hope this helps

Good luck!!