The short version
Packing cubes solve one problem: finding your socks without unpacking the whole bag. They're excellent at that. They do not create space. Rolled clothes in a cube take up roughly the same room as rolled clothes not in a cube, and "compression" cubes mostly squeeze out air you could have squeezed out with your hands. r/onebag says this every time someone asks, and every time someone buys compression cubes anyway.
If you accept that, the question becomes which cubes won't fail. The part that fails is always the zipper. Eagle Creek's Pack-It Reveal line, around $45 for a three-cube set, uses smooth, reasonably heavy zippers and is covered by a lifetime warranty against defects. The cubes are very light ripstop with a large mesh panel so you can see inside. Wirecutter, Pack Hacker, and most of r/onebag land on Eagle Creek for the same reason.
The complaint about the winner
The Reveal's thin fabric means it doesn't hold a shape when half full; it slumps. And $45 for three fabric boxes feels absurd to a lot of people, which is fair. Eagle Creek's older Specter line was even lighter but tore more easily; the Reveal is the compromise.
If $45 is too much
A Bagail 6-piece set runs around $20 and includes a laundry bag. The fabric is heavier than Eagle Creek's, the mesh is smaller, and the zippers are the gamble: some sets go years, some lose a slider in six months. At that price you can replace the whole set twice before you've spent Eagle Creek money. Amazon Basics cubes are a similar story, with one r/onebag owner "honestly not impressed" by how little they held.
Why not the others
- Peak Design Packing Cubes (around $30 to $40 each): beautiful, with a clever clean/dirty divider. Also the most expensive cubes on the market, and the tear-away zipper that lets you open them wide is the part owners complain about.
- Compression cubes of any brand: the second zipper adds weight and a failure point for a small gain in flatness. Fine if you already own them. Don't buy them for space.
- Neoprene or "ultra-light" cubes: neoprene is heavy; ultra-light silnylon tears. Ripstop polyester is the boring right answer.
Which one for you
Frequent traveler who wants to buy once: Eagle Creek Pack-It Reveal. Two trips a year, or you just want to try cubes: Bagail. Either way, buy fewer cubes than you think; two or three do the job in a carry-on.