It depends on the complexity and difficulty of your app. If it's very difficult to create then get the rockstar programmer with hopefully some average UX skills

It depends on the complexity and difficulty of your app. If it's very difficult to create then get the rockstar programmer with hopefully some average UX skills. If your app is not that complicated to make and intuitiveness matters a lot than get the UX guy. When you refer to UX guy do you mean he's a designer? Can't you give the programmer instructions for the UI? For example, I'm great with UX but I'm neither a designer, nor a programmer. I'm a perfectionist and I want the products to be as easy to use as possible, or to look very good.