Computer systems sounds like you'd learn the most technical stuff; servers, security, debugging. I'm not entirely sure of this, though, so don't decide based on my word.
Software engineering has to do with the processes and documentation involved in producing software in a company. (Requirements, design and implementation, testing, maintenance)
It sounds like human centered computing has to do with how people interact with technology, and might be related to cognitive psychology and graphic design, making things understandable for users.
I'm not 100% sure on any of these. I'm guessing that, as with many things, there will be overlap on what classes you take.
If you're going to work with computers, you'll probably have to learn some mathematical stuff.
Don't let it intimidate you; it isn't something that comes naturally to most people. Struggling without giving up leads to understanding.
If you really want to try to avoid it, it sounds like Human-Centered Computing would be the last mathy, as it's more concerned with human interaction than technical details.
