I have the 24 little boxes (90243). For $5 you can't go wrong. They hold quite a bit of the little pieces,
Another good thing about that one is that there's no rule saying that the little boxes must be kept only in that big box.
The one minor quibble I have about it is that the other ones (94456, 94458) are noticeably sturdier, and I wish the 90243 boxes were made the same way. Still, there's a lot to be said for having all of those small boxes fitting easily into the one larger carrying box.