Scotland have been matched up against Estonia, Wales, Serbia, Croatia and England during Strachan's reign as national team boss.
However, after watching his troops lose 2-0 at home to Belgium on Friday night, Strachan was adamant that Marc Wilmots's outfit are noticeably superior.
"That's the best team we've played since I took over," Strachan told BBC Sport. "Belgium were magnificent.
"It was like a heavyweight boxer up against a flyweight. They've got speed, height, strength and we don't."