I have a ZTE Optik (also known as ZTE V55). I've rooted a ZTE Force from FreedomPop using only towelroot, and it has it's own problems but that's a different story.
I've tried a number of one-touch root apps and used Kingo root on the computer as well but nothing works. Everytime I use one, it says root failed. I've sent requests to each of their devs and I've got nothing back in 2 years. If it's any help the most I've ever gotten from one of the app was my tablet would restart when I tried using Kingroot.
I really hope somebody could help me, I'm not a noob at this at all but I wouldn't call myself a dev, I'm more than comfortable with downloading apps off the web straight to my tablet because I don't have a PC of my own yet, I just wanted to put that out there.
I have used the following one-touch root apps, all have failed:
- Kingo root
(I have also tried using a terminal emulator to root but I just gave up after a while)