I have now created many, many client presentations in Apple Keynote. And most of the clients who request a presentation in Keynote rather than PowerPoint are proud that they are willing to use more design-oriented products. For many years, Apple Keynote was ahead of PowerPoint: a cleaner user interface, cleaner templates, those alignment guides that pop up when you want to position an object. And in addition, you were using the same product that Steve Jobs, the master presenter, was using for his slides.
With the latest release of PowerPoint, I think both applications are at par. With each one of them, you can create both beautiful presentations, and horrible decks full of bullet point slides.
The workflow of Keynote though makes me scratch my head. While more complicated tasks are taken care of very well, it is the basic functions such as changing fill colours, font colours, aligning, that drives me crazy. Too many clicks, and I am always looking where to click. Initially I though it was me, but after month and months of trying things are still not getting better.
PowerPoint has a more cluttered interface but after some time working with it your eyes look on locations/icons and you instantly click without having to think. The solution for both programs is clear: create space for one user customisable tool bar. PowerPoint for Mac had one, but it disappeared with the 2016 update, Keynote needs one.
The above partly informed the design of my own presentation design app SlideMagic. You actually need very few functions to create beautiful charts. Most reviews of software tools are still 1990 style: a comparison of features. What you really should be measuring is how fast/easy it is to get a decent end product. Hopefully Microsoft and Apple are not reading this post, so SlideMagic can keep its competitive advantage!
Image of an A380 cockpit from Wikipedia