I think the marketing option is better if you definitely know that is what you want to do. In the commerce degree you'll start with other stuff like economics, finance, accounting etc. If you like the other aspects of commerce and don't have a problem with starting out doing more subjects, then the commerce degree is probably better. If you know you don't like the others though, and don't think you can put up with them (I'm not sure for how long exactly) then go marketing I guess.
It is like a pyramid, you start broader with more subjects in the commerce degree, and then narrow it down as the years go by, and eventually probably specialise in one thing.