I thought by "Soldiers" you'd mean the actual "Soldier" class, in which they only really felt like a threat in FE10. They felt like the easiest and most basic enemy type to deal with, to the point of being laughable. In FE10, however, they had some of the most balanced stats, and they were decently fast (not nearly enough to double), fairly bulky and only hit the hardest behind Fighters and Armours.
Shadow Dragon's H5 takes this by a landslide, for me. You need like 3-4 guys to handle a single enemy.