I always used to use FCK Editor and its been a long time i didn't switch to a new one. But one day one of my client told me that he don't want to use FCK Editor as it is obsolete. So i was bit confused in choosing the editor. The confusion is not about the new adaptation to new editor but its configuration.
I have chosen CKEditor which is the next version of FCKeditor. The editor has been rebranded and completely rewritten. It is now much faster (the code has been optimized), loads faster (the number of files has been reduced, so the browser will perform less HTTP requests) and developers friendly.
You can download from here.
You should be keeping in mind that if you desire to have the upload option from the editor than one need to be familiar with image browser or ckfinder. I have implemented image browser in fckeditor. But i faced tough time in implementing image browser in CKEditor. So i decided to use CKFinder in the CKEditor.
Make sure after you download the CKEditor and configure it , you should refer readme text file found inside the ckeditor module.
To implement the ckfinder , just follow the link for the video tutorial. http://jesox.com/posts/how-install-ckfinder-ckeditor-drupal