Which paid engine to choose for an English-language forum?

Question

CMS

Share your experience, which paid engine to choose for an English-language forum?
There was an idea to launch a forum in English, I don’t have the strength or time to write my bike,
so who knows, tell me a good engine for the forum, preferably with a description of the pros and cons based on personal experience.
Main criteria:
1. Mobile version of the site (Basic condition)
2. Convenient design, or the ability to change the design without racking your brains and code.
3. Supports UTF-8 encoding
4. Speed ​​so that a person does not have to wait 5 seconds for pages to load.
5. Easily distributed to several servers, in case of heavy load.
6. Normal admin panel
7. You can tie authorization to the forum through another database
8. Ability to add your own modules to the forum
Thanks in advance!

Answer 1

Almost all of this can be done by any modern
IPB used to be, was happy with everything