It is you as a person, who apply for the visa, with you own personal money in your own personal account, and for the acquired time ( up to 6 months ) for the chosen Embassy.
Apply in the country where you have been conducting your business, and the Embassy may have a little understanding of you strange way having a business.
Read a lot of earlier posts from people who have applied earlier, to get the needed understanding of what you are preparing to do.
Especially when the bulk of your documents are on other languages than English or Thai, you should apply in your homecountry where the Embassy will be familiar with documents in that language and how they are formated, saving you to make certified translations of documents.
Furthermore you save money by staying in in comfort in your home, instead of traveling to a 3 country and stay there for the unknown period until visa is approved.