What are the recommendations for a good school to obtain an ED visa in Thailand that has a quick processing time?

AAA

Something to bear in mind is that you will have to actually attend classes and show you study so it's probably better to pick the right school on the right criteria rather than looking for the fastest one

It takes a month or two

Some schools may take a while if all of their classes are already full.

You'll need probably at least a full month left to be able to switch to ED from a tourist entry as your school will need to send all of your information to the ministry of education and wait for their approval, and then once they have that they will give you the paperwork to go to immigration and you need to have a minimum number of days left on your stay (14-21 days depending on the immigration office) in order to apply.