Both IIT Mandi and IIIT Delhi are excellent institutions with well-established programs in Electrical Engineering and Computer Science respectively. The decision of which one to attend should depend on your personal preferences and academic goals rather than the quality of the branch. IIT Mandi is known for its strong emphasis on research, while IIIT Delhi is known for its focus on applied technology.
Both colleges give an edge to each other in terms of placements and quality of education offered. If you aren’t certain of your preference yet, it's best to go for IIT Mandi. There are 2 main reasons why I prefer IIT Mandi to IIIT Delhi.
However, solely relying on branch change is not wise and you should analyze other angles also.