Region-wise, advantages of outsourcing AR development to Estonia are the following:
Affordable rates. Estonian software development vendors offer modest rates in comparison with other countries. The average hourly rate is usually around $35.
Uncompromised quality. European software vendors, especially Estonian ones, are well-known for their attention to detail and extremely responsible work attitude.
English-speaking specialists. All specialists that you will have to work with will boast good English speaking skills. It is a working standard for Estonian companies.
Flexible working hours. Even if your business is located in a different time zone, you and your Estonian vendor will be able to work this out. Developers are used to working flexible hours.