Where is the best country to apply for a DTV visa for Thailand?

Apply in your country of residence, since the bulk of the documents would be familiar to the Thai Embassy there, might even save money on translating documents to english or Thai.

Also you can wait in the comfort of your home, in stead of wasting time and money to sit in a hotel room in a 3. country.

Read the website of the Thai embassy, you will apply at, since requirements differs slightly, specialy about how long time the full amount of 500.000 Baht equivalent has been in the bank.

Agents can’t help you much, since you have to be outside of Thailand, and have to be and stay in the country you apply in until the visa is granted.

If you live in France, then France would be your best shot. Note they're slow, like 1 month or even a bit more for processing.

Use a agent , cheaper then the flight,hotell,food and more

I would say in the country of your citizenship.

You are correct that there are many reports that Vietnam is quite easy. I think I've seen some people say that Indonesia isn't too bad either, but I'm not sure about that.

I would definitely recommend not applying in France. The Thai embassy in Paris is the worst in the world. They don't process applications for weeks, and sometimes months.

Just be aware that you would need to be physically inside the country where the embassy you apply through is located. So you would need to be in Vietnam if you want to apply there, and you would need to show proof of your Vietnam entry stamp in your passport as part of your application.