What is the best mediawiki hosting provider?
There seem to be a few providers who offer this, what have you had
The Pro Webmasters question guidelines state that you should "avoid asking subjective questions" and, on that basis, asking which MediaWiki hosting provider is the best is problematic.
The secondary question is polling users for their subjective experience with different MediaWiki hosting providers - it's a perfectly valid question to start a forum thread, but StackExchange sites are intended to provide questions and answers, not discussion threads.
For clarification on the general StackExchange approach to handling shopping questions and recommendations, I would recommend Q&A is Hard, Let’s Go Shopping! at the StackExchange blog (which was the inspiration for the How to find web hosting that meets my requirements? catch-all answer).
The best factual information that the Pro Webmasters community can provide is how to search for the hosting provider that will best suit your particular needs at a given point in time - even if everyone agreed upon a hosting provider for MediaWiki, the odds are against that hosting provider remaining the favorite (or providing the same quality of service, or providing a price that is accessible to all askers).