It’s always better to code offline as there’s no chance of codes ever getting leaked. And if you absolutely have to, better use Codechef IDE.
As stated before, all the rest have similar features and you need to try them all out to find your perfect match. Each of them have their own learning curves.
I normally prefer something lightweight, like a text editor with built-in build and run option. Sublime Text 3 suits the best for me. It’s fast and highly customizable and has appealing looks and design. You don’t need to learn any commands to start typing there.
But if you want super speed go for something like vim/emacs. They do have a higher learning curve but it’s worth it.
However, I would like to point out that for longer or more complex codes debugging is difficult with text editors. You may wanna switch to a dedicated IDE with debuggers for that.
Lastly, it all depends on how comfortable you are with your system, and how much effort you want to give in adapting yourself with other editors.