Difficult question. Most of the strategy houses offer CDD as a service line, so its likely you would have some exposure to CDD anyway.
If you join a big 4 transaction services teams, its likely you would be spending a greater proportion of your time doing CDD.
CDD will give you a solid foundation in business fundamentals and a skill set that employers value. You will typically be working for banks / private equity firms - which creates some good exit options.
However, the hours can be a killer - lots of short-term projects, demanding clients and sleepless nights