I absolutely love https://www.draw.io/ !
I’ve used Visio a bit, and I’ve used Word a lot. This is better than both. It’s fast and it’s easy, and I don’t spend so much time messing around in right-click properties menus. If I want to change the line color of an object, I select it and I click the line color button in the toolbar. Choose color, click Apply. Done.
Saves in a special XML file, no biggy. It can also export as a PNG.
Did I mention that it’s web-based?
Try it. You’ll like it.