It depends on the audience you wish to serve and the needs of your area. Many organizations need them, from cancer patients to the known names and organizations.
I can tell you last year many organizations were not accepting hand made projects. Many were.
As for what is desirable? Same stuff that makes it desirable to us. I try to have no real difference in materials or skills in my donation/non-donation work. Ok, maybe I design a bit more fancy when it's someone I know, but it isn't much. More than once someone has seen something I made to donate and wanted that more than what I made for them!
Currently I am targeting my donations towards kids aging out of the foster system and making twin to queen sized quilts that are a bit fun and funky. I've sent quite a bit of my 80s fabric not so suitable for that to a group that makes hospice care projects. I think more for the family than the patient but I'm not so sure on that, only that it was a good place for my fabric to go soothing tones and colors and patterns.