The technology platform will normally be chosen to match your requirements. So the more details you provide about what you want to do then the more the discussion can focus on the platform features that will meet your needs.
This is a complex discussion that gets more complex the closer you get to looking at specific tools to achieve what you want. So I’m trying to keep this generic.
I think that the issues aren’t so much about about mobile app versus web app. They have more to do with other characteristics which I provide more detail about later in this post:
Centralise large databases and heavy calculations.
Centralise shared data.
Up-time/availability issues are complex. Centralised control and management is easier but network issues become more of a problem. Local apps with local data are probably the simplest way to get 100% availability.
Security issues are likewise complex because networks are a major source of vulnerabilities. Whereas local app security is largely offloaded to the local OS and antivirus.
Where platform apps and web apps then differ most is in the user interface and app store presence. Of the two, the user interface issue most favours native apps with full access to the device features. Getting into an app store is always possible, e.g. by creating a wrapper app with some additional unique features added to it. But it can be quit costly.
Back to discussing the more general issues I mentioned above:
Do you need high responsiveness or high performance? Native apps are more responsive and generally have higher performance for lower levels of processing power. Centralised servers have a big advantage when processing a large database or heavy calculations. So community forums with multimedia content are best handled on such servers.
Who generates and uses the data? The more data is shared then the more likely a centralised platform will be best. So if I have a community focus then most data will be shared with other users and is more easily handled using a web-based solution. Community forums exemplify this. Personal private journalling is at the other extreme because there is non need to share the data with anyone else. This favours a local app.
Do you need 100% up-time? A local app (local means running on a device that is with you) with local database is better if you need access all the time but a web app can provide access to data on all platforms. Say I am doing presentations on the road then I don’t want to have to depend on having a working network connection to deliver my pitch. So I will use an app on my device with all the presentation data I need stored on the same device.
Do you need local storage of all the app data? Generally, local storage means a local app too. While a web platform could be used a major weakness/issue is often how to store data locally. Formal cross-platform standards are still being developed.