I always prefer rolling myself, way less messy and if you are careful you don't need to do much prepping. I don't even bother with tape when I'm painting so I can minimize waste, except for really tricky spots maybe. I'll have paintbrush and roller and cut corners with paintbrush then roll the rest.
I've actually toyed with the idea of doing painting on the side. I'm not exactly an expert at it though, but I think it's one of few trades that does not really require any kind of license or certification so it's easier to get into. At least I don't think it does, never looked into it too deeply.