which app is better to work on with?

The kind of app depends on factors such as functionality and the size of the user base you desire. You might want to build a Desktop App if...

-the app has a lot of features/functionality the User can call upon (does "a lot" of things)

-the app is used to develop "documents" or complex projects for work

-you want a single app available to a lot of PC users (i.e., available on Windows 7 as well as Windows 8.1)



You would want a Mobile App if...

-All the necessary functionality can be implemented in a simple interface (does "a few" things)

-You want an easy hub for maintaining the app, hearing user feedback, and making a profit (Windows Store)

-You might find that developing a mobile app is easier than a desktop application (I did, though I wouldn't call it easy)



There are advantages and disadvantages to either one and you have to weigh them out. A Desktop app will be usable on most computers, but how many people will encounter your application (and how many will install it)? A Mobile app is available to fewer people, but those people are slightly more likely to see your app and trust it.



There is no right answer. I'm just offering guidelines, not rules, and you are free to disagree with me.