What are the experiences with ED visas in Thailand and the differences between government and private language schools?

I want to ask if any has used or is using the ED visa,and what experiences with the different schools like government or private. The fees for classes between the two types of schools and what would be the ranking of said schools from worst to great and of locations, are there limited amount of schools. I read an article about language schools in Phuket being overwhelmed by Russians so there was a rush to open more branches.

I plan on Bangkok or further south as the location I want to stay.

Thanks for any help.