This question comes up a lot. Do I really need a full IDE or can a nice code editor work fine for simple projects. A code editor will work fine for writing code, but the problem is that most of the time spent in development is not just writing code. Notepad++, Sublime, and Atom are excellent code editors, but any serious developer needs to be proficient in an IDE. Once you are proficient with an IDE you will feel very limited using just a code editor.
An integrated development environment provides a full platform for software development. It combines a code editor, compiler, and debugger into one tool. It will also provide features like code navigation(where is a method defined? where all is this method called?), package management, dependency importing, code management integration, and performance analysis.
Now that Visual studio 2015 is free, it is an excellent choice as an all purpose IDE. It is not just for .NET development anymore. With the inclusion of Xamarin and other items(like NodeJS tools), it can be used to develop MEAN stack applications HTML/CC/JS websites, Android Java applications, IOS apps, etc. It now rivals Eclipse for the breadth of platforms and languages it supports, and it is a more complete overall package(in my opinion). You can use Visual Studio for almost any development. Once you are familiar with it you will find developing with just a code editor very inefficient.