I am a Chemical engineer from IIT M.
The answer for the question varies depending on what you exactly you want from 4 years of college education.
BITS and IITs don’t differ much except for the IIT tag. But nevertheless BITS also has high reputation across globe.
So your question comes down to which branch you should choose; chemical or CSE..??
If you are planning for a MBA/MS/PhD later, there wont be much difference between the both groups.
If you want to just pursue any job in the particular discipline, choose CSE (High pay with considerably less effort) over Chemical engg (less pay-less effort: High pay only if you are top of class).
If I were you, I’d have chosen BITS CSE (Only Pilani campus).