We lost a lot of beloved characters throughout the Harry Potter series, including Harry Potter's parents, Lily and James Potter , Cedric Diggory , and Mad Eye Moody, but the bulk of those we lost died in the final battle against Voldemort and his horrid Death Eaters and on Hogwarts grounds, thereby making the majority of those we lost eligible to become Hogwarts ghosts.
In the world of Muggles, our world of staleness, capitalism, and unending boredom and poverty, it is generally accepted that when people die you will never see them again while you are alive, except, perhaps in dreams. But in the Magical World of Harry Potter, people have the option to stick around after death and become ghosts, or if you were a Headmaster or headmistress at Hogwarts, a magical, moving painting capable of keeping an eye on the students of Hogwarts School of Witchcraft and Wizardry even after death.
Since the second option is limited to those who have sat at the head Hogwarts School of Witchcraft and Wizardry as its leader and is not an open option for just any one of the magical world, we must limit ourselves to wishing for ghosts.
If you could have your wish granted, if you could vote, who would you have kept… even after death… as a ghost at Hogwarts no matter the location or circumstances of their death?