The following are the Lists of WYSIWYG Editor that you can pick:

• RadEditor (Telerik). AJAX-enabled.
• WebHtmlEditor (Infragistics).
  
• Cute Editor (CuteSoft)
• FreeTextBox (FreeTextBox.com). Free for basic edition. Source code available (for a price).
• Peter's Textboxes (Peter Blum). Suite of enhanced text box controls.
• UltimateEditor (Karamasoft)
• Asbru Web Content Editor (Asbru)
• ASP.Net XHTML WYSIWYG Editor (MoreNet)
• AspLib Component library (Astron Digital). Includes a WYSIWYG editor, among other things.
• ASPxHtmlEditor Suite (DevExpress)
• ComponentArt Editor for ASP.NET AJAX. (ComponentArt)
• EditLive! (Ephox)
• eWebEditor (eWebEditor)
• eWebEditPro (Ektron)
• InnovaStudio WYSIWYG Editor (InnovaStudio)
• FCKeditor (FredCK.com)
• Html TextBox (ActiveUp). Part of the ActiveUp.WebControls suite.
• Obout Editor for ASP.NET (Obout)
• pinEdit (Pintexx)
• PowerWEB TextBox for ASP.NET (Dart).
• RichTextBox (aspControls)
• RichTextEditor (Syncfusion)
• RTE ASP.NET Control. Released under an MS-PL license on CodePlex. Includes source.
• SmartText (Z-SoftNet)
• soEditor (SiteObjects).
• SPAW Editor v.2 (Solmetra)
• TinyMCE (Moxiecode). JavaScript based; open source under LGPL.
• Ueditor (Yardi). Free; source and restribution for a price.
• WebHtmlEdit Control (JitBit Software)

Good Luck!