2 50's if the tool you want to use it with draws too many amps the 100 may not supply enough power. Like an air compressor draws too much.
It's the other way around. Two fifty foot cords must be connected together; that's nowhere near as ideal as a hundred foot uninterrupted run. The hundred would be for higher draw devices.
On
paper, anyway. In the real world, I'd rather have the fiftys. I wouldn't want a hundred foot cable if I couldn't have a fifty to use, so I'd end up with two anyway.
Indeed, I have two fifty foot cords here for my generator. That gives me a lot of versatility.
A: One cord connected to a power strip running a limited number of devices, and another free to do something else; exchanging capacity for portability.
B: Both cords connected to the generator, which exchanges functional radius for an extra powered location.
C: Both cords connected together to reach otherwise annoying devices. Now you're exchanging everyday convenience for convenience in extreme conditions.
If I had a hundred foot cord, I'd be stuck with option C alone. I'd rather buy a hundred later if it was ever required than wait around cursing and eventually buy a fifty anyway.