Native hardware required

If your product or service will use a hardware component from your audience's mobile device or tablet, such as the GPS, the Camera, the Microphone, or the Gyroscope, then you should heavily lean towards building a native app.

There are web frameworks that will allow you to gain access to a devices' camera or GPS via a webapp, but none are as stable, reliable, or robust as using a native app framework.

The question then becomes, what operating system do you develop your native app in: Apple's iOS, Google's Android, Microsoft's Windows, other or all of them?

Keep in mind there are platforms – such as Xamarin – that enable you to develop in multiple native app ecosystems simultaneously, however, deciding the platform(s) will affect your timeline, budget and audience reach. Also know that if your product or service can or should be accessible offline, then that reinforces your native app decision and eliminates a webapp given they require connectivity to run on a browser.

Universal adoption expected

In contrast, if you are looking to sign-up a broad audience then you should lean towards building a webapp.

All devices, whether mobile, tablets or laptops, have sophisticated and modern web browsers that can easily run webapps. Therefore, if you don't want to worry about deciding between different platforms, then by building a universal webapp that is compatible with all popular browsers all your users will have immediate access.

This route also bypasses all the requirements you must meet and the policies you must comply with to publish your native app to communities such as Apple's App Store or Google Play.

Even better you can update and maintain your webapp at your own pace, not having to rely on Apple's or Google's approval and publish/update schedules.

Investment tolerance 

Now, if you gathered major seed funding or hit it big in a series A round giving you a higher upfront investment tolerance, then I'd advise you to go the native app route.

The aforementioned Apple and Google native app marketplaces, albeit strict, offer amazing features that you would not be able to leverage going the webapp route. Your customer experience will almost certainly be higher going native app, which will increase your ROI, promote repeat subscribers and overall success.

But this route will be more expensive than webapp, especially if you do decide to offer it on multiple major platforms. Hence, if you have the budget, go for it and launch natively. If your investment tolerance is more reserved, then start with a webapp, and simply iterate until you are forced to go native.