- Magnet for Mac allows you to split the screen into halves or quarters by just dragging and dropping windows. I love it and it works as advertised and I haven't really found any glitches with it. Another popular app is Moom. Moom doesn't use drag and drop though. Hope this helps!
- I've used Moom for the last couple of years. It works as advertised except for one small problem, which is that it sometimes switches Spaces when I'm attempting to drag a window to the right to have it snap into place. Happens rarely and there's probably a fix for it, but still often enough that it's worth mentioning.
I like this tool. It's simple, free and doesn't get in your way. You just set the hotkeys you want to use and manage your windows with comfort. It's also open source: https://github.com/eczarny/spectacle
A great window sizing and placement manager for macOS.