I use Sublime Text 3 but I may as well use notepad, I hardly use any of the fancy features. My favorite editor in the world is Vim, so I'm a pretty minimalistic guy. As far as indentation goes, most people use tabs (I prefer tabs) but some people decide that they want to make it a bunch harder to delete indentations and use spaces. Thankfully all good editors allow you to use tab to insert a certain number of spaces, cause I'd go crazy if it didn't.