I don't like bloat.
Whenever I develop, I want the absolute minimum of distraction that it's needed to complete a task.
I've been through many IDE/Editors (in order of discovery): Visual Studio, NetBeans, the JetBrains suite, SublimeText vi and Atom.
I started with C++ and C# and fell in love with VS. When I started working with Ruby, RubyMine looked like the only choice, and for many developers, it still is. For me... it's just too much.
I loved RubyMine but,_ _just like all the previous ones, it takes too much time to open, too much to index the project, too many buttons, too many settings. I just want to write code and see it working.
I went to SublimeText and now its OpenSource incarnation: Atom.
Sometimes, for smaller tasks or even small projects, I do enjoy using vi (beware: too many plugins and you have a bloated vi environment too).
For me (and in this moment), Atom represents the perfect balance of essential features and speed that I need when writing code. I can use the command line for anything not strictly required in the IDE, like Git, starting and managing the Rails server and setting breakpoints.
(Yes, I know. SublimeText is way faster than Atom when handling huge files. But do you really open 3+ MB files in your daily development job? You're doing it wrong.)