I think you're asking whether you should go PC or mobile.
The answer depends on your interaction model. Think about a messaging app. The user will be interacting with it briefly but many times through the day. This is an ideal model for mobile. By comparison, an app that requires them to type extensive text or otherwise concentrate for some time, is better done as a "PC web" app.
Another consideration is focus. A todo list manager can be a very simple, focused app which is also ideal for mobile, as you need to be very parsimonious when you lay out your screens on mobile. Look at Clear, an ultra-minimalist todo app for iOS. If you compare that to a complex groupware app like Asana, you can see that the extensive feature set means that it works better on PC rather than mobile.
If you want to talk more, we can have a call.
