The Stonemaier Games containers have two advantages: they're cheap, and they're small. When you have a relatively small number of items to store, especially if you have limited space for the container itself, they work well.
For example, 3 Stonemaier containers now live in my copy of Harry Potter: Hogwarts Battle, as they just fit in the side pocket of the plastic insert. There is 1 container for Attack tokens, 1 for Influence tokens, and 1 for everything else, which works well.
4 more Stonemaier containers are in my copy of Dungeon Lords. They're just the right side to fit directly on the central board. The tunnel tiles are a bit too bit, so I'm using a G33kbox GB1 to hold those.
It also worked well for the player cubes in Terraforming Mars; each player has a relatively modest number, and they easily fit.
They were just about the right size for resource tokens from Star Trek: Ascendency. The resource nodes and ships didn't fit at all; the G33kbox GB1 worked well.
The lids snap shut on all 4 sides, and feels very secure. However, it can the difficult to open them. I was regularly worried that I'd apply too much force and send wooden blocks flying across the table. It hasn't happened yet, but I feel I need to take extra care to open them.
Unfortunately the lids don't nest underneath the bases in any way. As a result, the containers don't stack. Similarly, you can't store the lid under the container while playing; the bottom will easily slide off.
The lids are very deep, making them a solid cup themselves. However, that depth seems unnecessary. You can slightly overfill them, but given the size they'll almost certainly spill out if you're not cautious. You could fill the lid, then use the base to shut it, but after you open it (presumably in reverse order), it won't fit in the base. Given that, the extra deep lids seem overkill, and I'd have prefered they be a bit shorter.
An accident revealed that the the G33kbox GB1 lids and bases are reasonably interchangable with the Stonemaier lids and bases. Its a bit expensive, but using a GB1 lid on a Stonemaier base is just about perfect.
The smooth curve of the base made it easy to remove pieces, but if the tray was relatively full of cubes, I found it easy to accidentally knock some out. Careful technique (reach in at the near edge and pull toward you, don't reach in the middle and grab), mostly eliminated the problem.
Overall, I liked Stonemaier Games plastic resource containers. They're cheap compared to the competition and reasonably well designed. Their big weakness is their small size, and unfortunately their large lids mean this doesn't translate into fitting into tight spaces.