Working files - External drive or dropbox

Wondering what peoples thoughts are on the best practise for working files and saving on devices please? I've always saved my work on an external drive and back up on a secondary one... this feels a bit clunky...

I've been looking into iCloud or Dropbox (only used this for file sharing until now) as an alternative way of storing and working on files, but guessing this is a probelm if there's no internet connection.

What do people find works well for them, please?

Thanks! 🙏