Atanasoff-Berry was an unreliable one trick pony.
They had some great ideas and a solid theoretical foundation, but for lack of expertise or maybe funding they couldn't pull it off before being called for the war effort.
There were several other similar machines around the world but they suffered the same limitations of being very specialized.
The Aiken-IBM was a full fledged computer that could handle any type of mathematical calculations.
IBM was hired as the contractor to build it because of their expertise in building business machinery (cash registers), but not because they knew anything about computers......that was all Aiken.
