I’d also suggest Arch assuming one has patience for some tinkering. Getting familiar with the Arch Wiki and the other resources that exist is quite useful even with other distros! Not to mention the better understanding of the system gained simply by following the installation guide.
Even if one doesn’t stick with the distro, the things learned setting it up will be useful down the line as well. The experience would also be very different from Debian based things, so it could be fun for a distro hop!
The package managers are actually a huge upgrade, at least in my opinion. I was always annoyed having to hunt for the right site for the right installer, now I can just search and install with a command without even opening a browser. But the biggest benefit is the updating. One command to update everything is so handy, one command and all my applications and drivers are updated just like that. But there is the issue of many programs simply not supporting Linux. For those you’ll sadly have to find replacements or workarounds.
If you want to get rid of Grub instead of what others have suggested, you could try booting into Windows and look for “advanced startup” and do a startup repair from there. That might destroy Grub and replace it with Windows bootloader again. If it works, your Linux stuff will remain on the drive, but Windows will boot like before. (you can easily reformat the HDD drive from Windows afterwards to use it for storage)
Some of my personal tips for moving to Linux: