Well, the indentation is part of the syntax, so you can't really avoid it. I personally like tabs, because they are easier for me to work with, but I understand it is a personal preference. Also, if you are using more than 2 or 3 levels of indentation, there is probably something wrong with your design.
That said, you can change the Godot editor's use of tabs or spaces in the settings. Click "Editor" on the top then "Editor Settings" then under "Text Editor" click "Indent" on the left. You should see now you can select spaces and set how many you want, if the editor should auto-indent, etc.
