While most of the experts that replied all have valid points, the main issue I see is that pushing any app down the monetize by paid ads method is in high risk right now because the next version of IOS will block ads, Apple is on the war path to kill ads on their devices. Why is that a problem? what % does apple represent in your niche? greater than 50%.

Subscription is the best path in my opinion, and yes the industry is shifting towards that model, not because thats what the users want, but it makes more sense for a business to offer subscription based services.

I could provide a more tailored answer if I knew more about your app.