When comparing XnView vs Image Viewer Ultimate, the Slant community recommends XnView for most people. In the question“What are the best image viewers for OS X?” XnView is ranked 4th while Image Viewer Ultimate is ranked 7th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Supports over 500 image formats
Pro Includes simple editing tools
Typical image editing tools are included. For instance, there are tools for color and size manipulation, several filters and effects.
Pro Available for macOS, Linux and Windows
Pro Easy redate and view configuration
Pro Compare images side-by-side
To delete blurry phone pics, etc.
Pro Multi-lingual
XnView speaks over 30 languages.
Pro Portable version for Windows available
Pro Watermark support
You can add watermark to bulk images.
Pro Slideshow and full screen
You view as slideshow or full screen mode
Pro Cactus digital
A pro digital compay recomendation on ease of use.
Cons
Con Very poor quality and very invazive on windows 10
Convert all images to 8bit rgb
[not suport 16bit or 32bit, cmyk, Lab, multichannel] so you never be able to see real original image, you only see the result of conversion...on windows 10 it enforced self promotion to default app for every type/format of image...
Con No Dark mode
Con No custom installation - if you need i.e. a language package, you need to install the full version
Con Free only for private use
For use in a company 1 license starts at 26 EUR.
Con Doesn't show movies on phone in correct position
Some of mp4 files shows in upside down position.