A Ripper TV show, even made 20 years ago, would probably not have starred Anthony, they'd have needed a younger actor. I think it would have been more like a mini-series really. I could see six episodes of young Giles and friends causing trouble in London could be interesting, but could not have seen five or seven seasons of it.
An Oz show...I could kind of see it. You'd start with a flashback to when he first leaves Sunnydale, spend an episode or two on his journey to bring the wolf under control, traveling the world. Then in the "present", we find Oz has settled somewhere, for some reason I could see him in New York City, splitting his time between trying to control his werewolf nature and using it to fight evil. Eventually, Willow comes to see him and helps him find stability using a powerful magical ritual.