ntex is written by the same person that started actix-web, Nikolay Kim (fafhrd91 on GitHub). There was a bunch of drama a while back due to actix-web using (what many reasoned to be) avoidable unsafe code, which was later found to be buggy. Nikolay was pilloried online, resulting in him transferring leadership of actix-web to someone else. ntex is, as I understand it, essentially Nikolay picking back up on his ideals for what could have been actix-web, if people hadn't pushed him out of his own project.
How ntex compares to the pre-/post-leadership change of actix-web, I don't know.
Here are some jumping points if you want more of the backstory.
https://www.theregister.com/2020/01/21/rust_actix_web_framew...
https://steveklabnik.com/writing/a-sad-day-for-rust