For Computer Science CSA is the preferred one for CS students.
CDS (formerly SERC) is good for supercomputing and distributed computing related areas.
DESE (formerly CEDT) is good for embedded systems and related areas.
Usually placement opportunities are same for all though some companies say only CDS - if they want supercomputing people, some only CSA - if they want general CS etc. If no special interests, CSA is better.