When comparing DaisyDisk vs F.lux, the Slant community recommends DaisyDisk for most people. In the question“What are the best power user tools for macOS?” DaisyDisk is ranked 7th while F.lux is ranked 26th. The most important reason people chose DaisyDisk is:
While working on your Mac you create and download a lot of files, but rarely delete anything. As time goes by you have less and less room for your data. DaisyDisk finds those hidden unused gigabytes.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Helps find and delete files taking up HDD space
While working on your Mac you create and download a lot of files, but rarely delete anything. As time goes by you have less and less room for your data. DaisyDisk finds those hidden unused gigabytes.
Pro Awesome visualization of files on drive
DaisyDisk gives you a perfect overview of all the disks connected to your Mac, be it Macintosh HD, flash card, Thunderbolt disk or network storage. And does it in a beautiful way.
Pro Can help sleep better
Helps provide better sleep for more energy during the day.
Pro Eases eye strain
Decreases color temperature at night, changing the normally fluorescent blue of an LCD monitor to a soft orange. Much easier on the eyes, especially in a low-light environment.
Pro Subtle transition
The transition from daytime to nighttime color modes takes an hour by default and will detect your current timezone, meaning that it will happen in the background at sunset, often without you noticing.
Cons

Con Calculation based on 1000 not 1024
It's nice to have a base 1000 (MB, GB, …) calculation but it should be optional. Default should be 1024 (MiB, GiB, …)
Con Expensive for how often it is used
Con Takes a while to get used to
After installing F.lux, the screen will look a lot more yellow. This takes about a week to fully get used to. You can ease into it by setting the color temps higher than the recommended defaults.
