So in your case based off what you have said neither of these visas are eligible for yourself as you can’t complete a language course if you are in and out the country every month. A multi entry tourist visa could work and then for the rest of the time use exemptions?!
Most embassies/consulates are asking people to apply for an ED visa instead which in all fairness sounds more suitable. I mean why do you need to a 5 year visa to learn how to cook Thai food 😂. They should never have included that in the DTV as the ED visa in place for those sorts of activities
So your tourist visa will run out and you will come back into Thailand on a visa exemption? As long as you are from one of the qualifying countries then you will get a 60 day visa exempt stamp