One thing that puts me off Stella is the fact that she doesn't seem to be willing to take risks and that's an important thing for an entreprenuer to have. However, Chris' flaw is he does seem to drone on during presentations. Other than that though, he seems pretty intelligent, he's young and I think he has a lot of potential.
On the other hand, there's Stella, whom I do feel is a strong canditate but I can't help feeling, as I've mentioned, her unwillingness to take risks is going to be what stops her from being hired - if she isn't hired in the end.