I think a lot of it depends on the application and how people are intended to use it. I see a lot of services and apps that start out as web applications and end up with a mobile component. As an example, if your coding a business application dealing with data entry, you would probably want to start with a web version. A mobile version might give you other functionality, but the majority of the app is in the web version.
Thank you for your input! Yes, with your opinion and others added, I will create a web application first. From design, it will be mobile responsive and later -if deadline lets me- release a mobile app with some extra functionality. In this priority-order.
With this and since deadline makes me start from now on, I consider this discussion closed.