Something I didn't mention is BT is terrible for music (for more on this, read here:
https://www.howtogeek.com/354321/why-bluetooth-headsets-are-terrible-on-windows-pcs/)
I'm not the only one who isn't exactly enamored with BT (for some reason, I can't insert links on here). Check this one for an example:
Why Bluetooth has so many problems and issues - Business Insider
Do a search on BT problems and you will get page after page on how to fix them (none of which ever worked for me, btw).
BT5.0 is supposed to better but just try and find a USB BT dongle with 5.0. They just don't exist. About the best you can do is 4.0 or 4.1. There are BT 5.0 transceivers available but they are bulky things that connect to the computer via a USB cable, not a nice, compact dongle that doesn't get in the way.
I've owned three BT dongles in my life. One I never could get to work. Period. The other two, both ASUS, worked just fine but, the first time I tried to pair one up with my cell phone so I could download pictures on the phone to my Win 7 desktop computer, it took me hours (and some pretty colorful language) to figure out how to do it. None of the directions I found online would work. Even after the first time I finally got it to work, the settings wouldn't "stick" and it took a while to get figure out how to get them to "stick" so I wouldn't have to start over again every time I wanted to download a picture from the phone.
Getting the second ASUS dongle to work on a Win 7 notebook took less time since I already had an idea how to do it but it still took a bit of doing.
The only reason I bothered with BT is it was the
only way to get photos off my phone. Btw, the phone's directions for connecting the phone to a computer via BT didn't work.
In contrast, the RF Logitech Unifying Receiver is simple to use. Install Logitech's Unifying software, then follow the prompts to easily and quickly pair the dongle with up to six any of Logitech's compatible devices. Once paired up, one can move the dongle from computer to computer and the devices will stay paired up (sadly, a device can be paired to only one dongle). No hunting for obscurely named MS programs, like fsquirt.exe (seriously, MS? fsquirt?) that no place I found online knew about.
The reason BT is less secure than proprietary RF dongles is more devices are likely to have BT connectivity than with a proprietary dongle.
It might be different for a computer that has BT built in but, for those that do not, BT is a pain in the neck (polite term).