Hi aspirant,
Computer science with specialisation has grown in importance as now there are lot of posts available for experts in these fields.
Data scientist analyse the previous data and information available and develop tools and strategy for the better optimization and productivity of goods. Internet of things deals with network security and developing new softwares to share data among the people and systems in secured way. Block chain technology is a special technology developed for the security, maintenance of crypto currency and confidential data by interlinking all the system forming a chain.
Preference should be based on your interest but I will suggest you Data science> Iot>Block chain based on demand.
Hope it helps!!