Pixea is an image viewer for macOS with a nice minimal modern user interface. Pixea works great with JPEG, HEIC, PSD, RAW, WEBP, PNG, GIF, and many other formats. Provides basic image processing, including flip and rotate, shows a color histogram, EXIF, and other information. Supports keyboard shortcuts and trackpad gestures. Shows images inside archives, without extracting them. And it's free!