During this time, it was the major European countries that were the important powers in the world. They were the ones with large empires and the serious power in the world. Most of the European powers at least took a turn at being a major power.
The biggest power early in this time was Portugal. They were in control of the trade around Africa. The Spanish took the greatest power soon after that as their conquests in the Americas gave them gold and silver and other types of wealth. Through the whole time, both France and Great Britain were quite powerful. Even the Dutch were powerful enough to colonize Indonesia. All of these Western European countries were quite powerful on the world stage at one point or another in these three hundred years.