The answer to this question is it depends on the product you are selling. In todays world as majority of people use mobile, so mobile app has become more important part, but cant ignore the web too.
You can do a poll as to check what your customers want , what are their preferences.
You can also do a deep research of your competitors and check what they are doing, how they are engaging more.
If your product needs GPS locations then , then mobile app is the best solution.