I realy like the editor stackoverflow uses. its nice, plain and simple. Also I realy like the auto image upload to imgur.com Is there any editor out there which can give me the similar functionality specially the image upload feature
Stack Exchange websites implement Markdown, and also a couple extra special features (imgur uploading). If you implement some text editor with Markdown, it will have many of the same features.
See: markdownsharp, and the blog post here.