AI Gigapixel was the first standalone Tool for the pure task of upscaling images.
Because of that, AI Gigapixel feels really refined and is extreme reliable. Personally, I never had a problem with crashes or bugs. And I also like the UI, it just feels finished.
It comes with 5 different algorithms, one specifically for Art & CGI which can be helpful if you are searching for an option to upscale AI generated images.
There are also settings, to remove common issues with images like noise removal or Gamma correction and a Face Recovery Option, to improve the upscaling of Faces.
Also, the before and after comparison works really well and is really quick.
Overall, it is my favorite Tool and the Tool I am using personally.
The only issue I see is, that it now costs $99 (one time purchase) which I think is a bit too much for a Software which only fulfills one task even if it fulfills it good. Which is the reason it only makes sense for people, who either use it really often or people who use it professionally and really want to get the best results. Or people who work in a Company and don’t have to pay it themselves.