All the topics you have mentioned, have really good options in the Industries. Now I would recommend that going for the Block chain or Data Science will be a very good choice. The recommendation is based on the number of openings per company available for such specialized engineers. So you have a lot of vacancies available for this technologies. Now Cloud Computing and IOT can be a good option provide you should have very good understanding about this. This fields are still developing and have very active region of working. So until and unless you are 100% suitable for it, it would be hard to get the job. Companies recruit less Cyber Security engineers as a result its a demerit from the job perspective.

You can follow the above strategy to have a good career ahead.

To know more about IOT, visit the link below:

https://www.careers360.com/courses/internet-of-things-course

To know more about Data Science, visit the link below:

https://www.careers360.com/courses/data-science-course

To know more about Cyber Security , visit the link below:

https://www.careers360.com/courses/cyber-security-course

To know more about Blockchain course , visit the link below:

https://www.careers360.com/courses/blockchain-course

To know more about Cloud Computing, visit the link below:

https://www.careers360.com/courses/cloud-computing-course

I hope this answer helps. All the very best for your future endeavors!