Operating system

Typically you are always better off running the most current macOS your machine will allow—especially for the built in security features.

Old app compatibility maybe one reason to hold back— you have to do your own homework here: https://roaringapps.com/apps

32-bit app compatibility with macOS High Sierra 10.13, Mojave 10.14, Not Catalina 10.15 ... - Apple Support

https://support.apple.com/en-us/HT208436

-----------------------------------------

https://www.apple.com/macos/catalina/

macOS Catalina - Technical Specifications - Apple Support

https://support.apple.com/kb/SP803?locale=en_US

System requirements macOS 10.15 Catalina

macOS Catalina will run on all Macintosh computers that supported Mojave:[1]

MacBook: Early 2015 or newer

MacBook Air: Mid 2012 or newer

MacBook Pro: Mid 2012 or newer

Mac Mini: Late 2012 or newer

iMac: Late 2012 or newer

iMac Pro

Mac Pro: Late 2013 or newer; Mid 2010 or Mid 2012 if upgraded with a recommended Metal-capable GPU

---------------------------------------------------------

macOS 10.14 Mojave - Technical Specifications:

https://support.apple.com/kb/SP777

Upgrade to macOS Mojave - Official Apple Support

https://support.apple.com/macos/mojave

https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12

MacBook (Early 2015 or newer)

MacBook Air (Mid 2012 or newer)

MacBook Pro (Mid 2012 or newer)

Mac mini (Late 2012 or newer)

iMac (Late 2012 or newer)

iMac Pro (2017)

Mac Pro (Late 2013; Mid 2010 and Mid 2012 models with recommended Metal-capable graphics cards)

Catalina (10.15) is the most recent.

You should also be able to use the online version, I don't since I prefer the security of keeping my own data.