If you're wanting a slow cooker primarily for bone broth, I'd check out pressure cookers. I have the patience of a five year old, and every few years I buy a slow cooker, realize I don't like waiting that long for something, then take it back.
A pressure cooker takes a couple of hours to make good bone broth rather than overnight. Reputable brands are now very safe (although my old one which I bought at a yardsale never gave me any problems either). I got a stove top one last month, but that's only because I have very limited counterspace where I live and I get tired of the small appliance shuffle when I have to use something on top of my counters.
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine