Ultimate Nofollow works great!
The description looked good to me, but after reading some comments that said it added nofollow to ALL the links I didn't want to use it. I want full control and do not want "nofollow" added to all of my links automatically.
But I tested it anyway, expecting disappointment, and I'm glad I did. I tried it on various links and images, over multiple posts. The source text of each published post verified it. Adding "nofollow" to one or more links, did not affect any other links.
It is easy and elegant. No new icons were added to the editor (it uses the standard link icon) and no special setup is needed.
Very NICE! I highly recommend it.