Here are some MacOS (and iOS) applications which I use all the time.
Having a tool to reliably and securely store a lot of passwords is essential for almost everyone nowadays. 1Password does that and keep them synced across devices. This is my top pick because if I were to loose this tool it would take me a long time to recover, both the access and the piece of mind.1Password Website
Things is a well thought out and beautifully designed app to keep track of todo items. Many people use OmniFocus, which also seems to be a great tool, but I don't need the extra power. I normally have to use Jira to keep track of work items, so I just need to keep track of all my non-work things.Things Website Things on Mac App Store Things on iOS App Store
Sometimes I want my window to be full-screen, but not the full-screen that hides the menu bar, like what the green button used to do before full-window full-screen was a thing. That's why I got Magnet. If I pull a window to the top of the screen then it automagically snaps to full screen. When I have my external monitors attached it is also useful for arranging VSCode to take up 2/3 and iTerm to take up 1/3.Magnet Website
Spotlight used to be great, but now it struggles to show the most relevant results. And, it's so slow at times that the results will change just when you are getting ready to choose something. Also, I'm a terrible speller and Alfred offers spelling corrections.Alfred Website
This app gives very good hyper-local, short-range weather forecasts. Do I pack up and go home or stay and wait out the storm? This app has helped me choose wisely many times.Dark Sky Website
Update: Now I just use the built-in terminal command
Caffeine is a tiny program that puts an icon in the right side of your menu bar. Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers. Click it again to go back. Right-click (or ⌘-click) the icon to show the menu.Caffeine Website