I have to start with the official Microsoft Power Apps blog. It has many contributors, largely Microsoft program manager, including frequent posters Denise Moran, Greg Lindhorst, Kartik Kanakasabesan, and Adrian Orth. This is the place to go for product announcements, updates and technical how-to for a broad range of Power Apps topics.
April Dunnam has been a rising star for years, formerly on SharePoint and now devoting herself to Power Platform. April offers highly understandable explanations of Power Platform, Dataverse and other top Power Apps topics. She joined Microsoft in late 2019 and has a thriving YouTube channel.
This is one of the most extensive and best organized blogs on Power Apps. You can dip in and read individual posts or read it more like a book with the posts as small chapters. In 2021 Carl received the Microsoft MVP award.
Nick Doelman is Microsoft Business Solutions MVP and covers the Microsoft Power Automate platform, with special emphasis on Power Portals.
Steve's blog targets the Microsoft partner community, with analysis of Microsoft's partner model and strategy, interviews with Microsoft and partner insiders, and his trademark ambush phone calls to Redmond. He reads his blogs so you can consume them like a podcast. Steve is blunt and irreverent, so you can count on him for a smile or a groan with every post.
Hardit's blog is devoted to Power Apps how-to articles. If you wonder how to take Power Apps in new directions, his articles will spark new ideas for you.