The best Muay Thai places don't offer visas. They are focused on building fighters and their fight teams and don't have the capability for that kind of headache.
Of the schools that I know that do offer Ed visas. Luktupfah may be the best one.
If you have zero experience in martial arts, the first three months at these ED visa schools will be OK.
And yes, my opinion matters. I work at the highest level of the combat sports industry in the region.