Hello there. First let's understand what both of these concept are.

Cloud computing is something in which you are working on a virtual memory which is having almost everything stored inside it. You can directly access all those resources without getting them on your system.

DevOps is a concept which has become a requirement of day to day industry work.

So basically what was done before was that a separate development team was made which was responsible for developing the project and have nothing to do with clients. A separate team was responsible for providing the project to client and dealing with all the conversation with the client. But in today's scenario it's required that the developer had the skill to interact with the client and handle all the problems by arranging meetings with the client. It has proved benificial as the developer is interacting directly with client which make it easier to make the client understand about the project.

So among cloud and devOps, cloud is a complete technology which is going to be one of the trending technology in near future while devOps is a skill which is being required now a day in all the employees.

So even though you becomes a cloud engineer you will still need to be a devOps . For learning about devOps what's required is that you should be having proper communication skills as well as developing skills so that you can deal with the client in every possible way.

In my opinion, I would go for Cloud computing.

I particularly find the cloud computing courses online really helpful. Like the ones on Coursera, EDx and such. They are really cool one to begin with and easy to start as well. Surely there are so many amazing books out there that can drill the advanced knowledge in, but these lecture series can be a good start.

You should at least know: Computer Architecture, Networking, System Software to start off.