Difficulty here is mostly a function of two things: how high off the floor you are, and how unpredictably the surface moves. Start at the bottom of this list and stay there until it is boring.
1. Foam balance pad — about 2 to 2.4 inches
A dense foam slab. The surface compresses unevenly under your foot, so the muscles in your ankle and hip do constant small corrections. This is where essentially everyone should start. Falling off a 2-inch pad is a step, not a fall. Our shortlist favors the 19 by 15.8 inch one because it has room for two feet side by side with margin, and that margin is the difference between an exercise and a stumble.
2. Inflatable wobble cushion — 2 to 3 inches
An air-filled disc. Its difficulty is adjustable: let air out and it is nearly a firm pad, pump it up and it is genuinely unstable. That is a real advantage — it grows with you instead of needing replacing — and it doubles as a chair cushion, which is how most people end up using one daily.
3. Rigid wobble board — about 3.15 inches
A wooden platform on a fixed dome. It tilts, predictably, in whichever direction you lean. A clear step up from foam, and the one balance product on this site that publishes a weight capacity. Its own listing warns against use on a wet or smooth floor, which rules out a lot of kitchens.
4. Spring-mounted board — 6 inches
Well made, 350 lb capacity, birch construction — and we tell you to skip itif you are a senior beginner. Six inches is about a stair riser, and springs make the platform move unpredictably rather than in the direction you lean. That combination is the opposite of what someone with a fall history needs. It is in our shortlist anyway, marked as a skip, because “why not this one?” deserves an answer.
And separately: parallel bars
Not a balance challenge but a balance aid— six feet of rail on both sides, so a genuinely unsteady walker can practice steps with a hand on each. The honest caveat that most listings bury: it anchors into your floor with eight expansion screws, which in a rental or over a finished floor is often a deal-breaker.