Hi Leigh,
There are tonnes of project management tools/apps out there but it comes down to what you need the app for, how big your team is and what you can afford to spend on it!
For example, if you're using it for yourself or a small team to share work, ideas, to-dos and a shared calendar I'd recommend Asana, Tameday or Basecamp. They are really simple to use and uncomplicated, meaning you can start using the software straight away without a steep learning curve.
For content strategy, you can't go wrong with old faithful, Google calendar. Another few favourable mentions would be Coschedule, Monday and SEMrush.
To be honest, I create a lot of content for our company and I've tried quite a few dedicated content strategy tools in the past but I've found them all bit OTT—just too many options really and more suited to larger agencies.
For a comprehensive list where you can compare apps, have a look at Capterra.
You can see what's suitable for your needs and view in-app screenshots.
