What is the best visa option for staying in Thailand for one year with multiple entries?

Typically, if you stay away a month and you enter by plane you'll be allowed in. There is no formal limit. No visa required. But if your trying to live/work here without visa, you'll run into problems eventually.

I don't understand the obsession to stay/live exclusively in Thailand exclusively and not stay other places for a month or so, too...

If you are under 50 there are very few one year visa extensions that will allow you to freely travel around, without your extension being voided, and they all require large sums of cash, with some requiring full background checks. If you try to border bounces you'll get two, with a good change of refused entry the third time.

I literally just went to language school today. If you want multi entry, or plan to leave whenever you want, the education visa will NOT be an option for you. Unfortunately there is no long term (over 60 day + 30day extension) multiple entry visa available for people under 50 years old, aside from the elite visa.

Just setup and register a school, make a curriculum and teach people something, plus hire 4 Thai people. That should be all you need to do to do it yourself.

If you want a simple education visa, you can go to the school or go through an agency and it's exactly the same price.

If you don't want an education visa and are over 50 with 800k in the bank it's easy too. Do it yourself 1900 baht.

If you are over 50 and don't have 800k in the bank go down some back alleys and you will find someone who knows someone who knows someone in immigration and you'll pay and get a visa.

So you want to bounce out and in every two months? You do realise that eventually you'll be denied entry? You can't keep bouncing. You'll need to spend substantial time in neighbouring countries

Education visa although if you’re leaving the country more than a couple of times a year they might ask why you’re leaving so much if you’re studying.

Otherwise it’s back to your country to get a multiple entry tourist visa.