Nothing is perfect, but here are a few things I enjoy using:

https://www.geogebra.org/calculator

https://regex101.com/

https://gchq.github.io/CyberChef/

https://www.figma.com

https://www.affinity.studio

https://bluecinema.ch (To buy movie tickets for a certain movie chain in Switzerland. I haven't used this in many years, but at first glance it looks like I remember it. Back then, this was a very smooth experience both on desktop and mobile. Just perfectly done.)

Any spreadsheet program (it's the spreadsheet itself, which I like, not necessarily how the UI is aranged around it)

Apple's Spotlight, GNOME's similiar thing (don't know the name)

I also like Tantacrul's interface design work: https://www.youtube.com/@Tantacrul/videos