If you live in another country, or travel abroad often, but would prefer to be treated in Bulgaria, you need to think about how you'll organise your visits to the orthodontist. The main appointments can be planned in advance, but unplanned visits may also be needed if something becomes uncomfortable. With braces, this can mean a bracket coming loose, an archwire shifting out of place, a broken metal part and similar problems. In such cases it's important to have access to an orthodontist nearby who can help you. If you choose fixed braces, the best option is to find a specialist in the city where you spend most of your time. If you're planning to travel, however, aligners are the better choice, as they need fewer visits and are less likely to lead to urgent situations involving discomfort.
This answer is for general information. Your own case needs an examination by an orthodontist.