Why does everyone do Disney witches? The problem with most modern witches is that they seem to be more plot device and less character. If they are evil, they cast spells that curse, transmogrify, or blast their target, and are interested in taking over the world, or at least a significant part of it. At the other end of the spectrum, the white witch heals, cancels out evil magic, and gives out good advice like lollipops. You can also tell the good from the bad based on physical appearance; the good are attractive and the evil always have some flaw with their appearance. We can do better.
The problem is that somewhere along the way pagan rituals changed. Originally, they had nothing to do with any Christian concepts whatsoever; the pagans practiced human sacrifice, celebrated their priests, and basically had a lust for life. Then paganism died off as Rome died and the pagans converted to Christianity. The problem is that somewhere along the line, the Old Time Religion, and by this I mean paganism, was resurrected, but without the teeth of the old paganism; too much of it just seemed rebellion against organized religion and industry rather than a celebration of life, and it became a bastion of feminism, celebrating the ideal of the feminine. Suffice to say that any mention of human sacrifice will be met with glares. I'm sort of in the weird position that I respect a lot of Wiccans that have found their version of the divine, but too many of them seem stuck more in the political rather than spiritual.
The problem is that this changed the perception of the witch as well. The witch became a victim of history rather than villain; rather than the deaths attributed to really bad ideas of the era, people looked at the deaths because of the Inquisition (yeahyeah, I'm again in a weird position here; yes; there were a lot of innocent deaths, but at the same time there was also a lot of bad medicine; a look at medical books of the time show a lot of deaths due to those trying to save people, and a lot of witch cures were based on poisons). Thus the witches of the fairy tales went from being creatures of evil to comic figures at best, and this has affected how we perceive them now.
I sort of wish that the old witch would make a good comeback; I want a woman who is powerful enough to take on a group of adventurers and kick butt in her own right, and knows exactly what she wants. Give me another Morgan Le Fey, and not that whiny version in the show "Merlin", but the witch of legend. I want someone who is not afraid of a little human sacrifice every so often, and is more than willing to put her own interests ahead of any of her followers. Sure, she can be after some personal revenge, but I want a woman with serious spell power who is willing to use every tool in her toolbox to make a serious attempt at world domination.
Either that, or the master manipulator that is Glenda. Here is a woman who got the shoes of power, got someone else to kill her rivals, and came out looking like she was not only innocent, but was acting in the interest of Oz. That is some serious spin control. Has anyone ever questioned the origins of the tornado that brought Dorothy to Oz and squished the "wicked" witch of the east? She just took advantage of the situation and acted quickly; she is not someone that you want to tick off.
I even do not mind the Cinemax witches that use glamours and charms to bend men to their will. They are not afraid to take some risks, deal with competition as it comes up, and have an actual plan to take things over. I appreciate that the main reason is that they are cheap to film and keep up the fine Cinemax tradition of sex over art, but at least they are fun to watch. As opposed to, say, the Disney version where they just seem to be a plot device. There are exceptions, such as Ursula, who wanted revenge, but it's just way to easy to think of the witches in just about every Halloween movie that Disney puts out.
So when you are thinking about your witch, have some fun with her. She needs to be evil, has to have access to some reasonably powerful magic, and has to have an actual motivation for what she does beyond "this is what the plot needs me to do." Do that, and you will have a witch that people will love to hate.