Founder of ARCom, WPDeveloper etc. I do read a lot and I write too, I foundered The Tech Journal, The Dhaka Times etc and serving information to millions. I invest and love to help startups and proudly involved with Trance App, Leanplum, FutureStartUp, Facebook and several other companies from their early stage. Among many other things I was an Early Google Glass Explorer, and I appeared in various (25+) WordCamps around the world.
The answer is what you do best!
I have seen from programmer to UIX Engineer to Marketing or someone who dont know any of this managing App Developing Team. As any other business knowing HR and having clear vision and understanding of the industry is most important. In generally a Mobile App StartUp should not be a very big Team, I am assuming 3-10 is ideal team size. But retaining good developer and designer in most demography is a challenge. If you have not a programmer you could hire a CTO, if you are not a marketer you could hire a CMO. But to really run a company like Pro, a insider you have to have clear idea, which language, framework platform you are using, how marketing for your specific sector. You dont have to code, but you need to have basic idea, so you could at least understand your team's work load and time frame. Or you could also have a co-founder who knows what you don't.
I hope it gives you some idea. I could give specific answer if I know your specific situation.
Best of luck!