Waterfall works when it's done right in the right environment. It's a nightmare when it's not. Agile works when it's done right in the right environment. It's a nightmare when it's not.
Having a good project manager who understands what it takes to succeed from a management/executive perspective and who understands how to keep engineers both productive and happy is priceless.
During the waterfall days, you would run into managers who would gannt everything and harass people into meeting deadlines for whatever would solve the 8 word description of the item on the chart. These days, you run into managers who are happy to distribute a jira ticket to resolve anyones gripe.
And then there are the thoughtful ones who understand priorities, factors for success, and how to set reasonable expectations on both sides of the table (for the techies and non-techies)
In the end, it's not the process you follow, it's the results that matter.