First of all it depends on your area of interest. But when we see the recent scenario computer Science(CS) is emerging field and there’s a lot of demand for CS Engineers(Coder, app developer, Networking etc). So there lot of field and all them has lot of scope in future. India is also turning out to become a hub in IT sectors.
But when it comes to mechanical it’s a totally different scenario. It totally depends on your interest. There are people who just take it based on payscale. So never do that. There are various specialisation which gives better opportunities and future scope. Such as CFD, Design, TQM, Thermal this field provide great exposure in this field and there much great demand for this engineers.
Choose wisely Both the fields are good and they have equal demand of specific specialisation in the respective field. Which will provide you handful opportunities.