Both IIT Delhi and IIT Roorkee are prestigious engineering institutions in India. Known for their excellence in academics and research.
However, the choice depends on you and your preference. According to me, IIT Roorkee is a better choice than IIT Delhi.
I am eligible to answer this question as my sister is a pass out from IIT Delhi, Energy Studies. According to her, the primary step is to determine what you want from your degree; is it a brand name you are after or do you want a better branch that offers quality MTech education?
As far as Energy Studies are concerned, the career prospects from campus are bleak with only 1-2 students getting placed from the entire branch. This branch is suited for those who are preparing for IES IAS. This is because the workload is considerably less in comparison to other branches sparing you enough time to prepare.
But if you are genuinely interested in pursuing a career in Energy Studies and subjects like renewable energy intrigue you, you can always go for off-campus opportunities which are in abundance.
As far as Control System Engineering is concerned, you can find more job opportunities in the field for energy engineers than for a control system engineer.
For either branch, the option of teaching as a job opportunity is always open and can be considered.