I love a feature of notepad++ where when you have documents open and exit, it won't bother you with a save dialog and when you open it again the previous state will be there. I found that mousepad on linux can do this.

For something functionality close I would look at Kate.

Geany. Both npp and geany use the same editor component.

Sublime Text. I think it's better than Notepad++ and is available for all computer platforms, not just Windows.

Sublime maybe?

vim :)