question about website creators

Hi,
Sorry for my English - I'm from Poland.
I'm looking for good website creator sth like wix but really important for me is to put the site on my own domain and it would be great to put it on my own hosting.
I know that wix supports this but I need cheap tool because I need more than 100 websites. Do you know a webite creator that supports multiple sites and domains and there is no information about this tool like "proudly created by..."? I can pay for it but don't want to pay 10$ montly for every website.

I know that I can use wordpress etc. but I need a tool to make modern websites really fast.

What's wrong with using Wordpress? It is the theme you then use that creates the look and feel of the site - so not sure what you mean by modern??

Isn't wp really fast.