I've done both on the same project. In my case, I had machine pieced everything but my machine broke when I was ready to quilt my watermelon lap quilt. Money was tight so I couldn't get the machine fixed right away. I had taken a beginning quilting class that had taught me how to hand quilt and I had the supplies so rather than wait forever to get the machine fixed, I just pulled out the stuff and started to hand quilt. Got about half of it done and my wrists started acting up so I quit.
Several years later, I found the quilt and wanted to finish it in time for a local show and tell so finished up with the machine quilting. I was really happy just to have finished a UFO and I liked the quilt enough to start using it.
Anything goes! As long as you are happy, who cares! Folks enjoyed it at the show and tell, and my family likes it so I'm happy with it.