Burma or Myanmar
It depends on who you ask
In 1989, the Military Junta renamed Burma to Myanmar in an attempt to improve their ethno-nationalist credentials.
Many in the west continue to use Burma in disdain for the Junta. While I was in country in 2013, I asked the young what they called their country. Their answer was Myanmar, not surprisingly since that was what they knew it as most, if not all, of their lives.
While a variety of their elders may still refer it as Burma, I will defer to how the young in country told me.