The Yamaha FC4A is the one to buy by default. It is the pedal the r/piano thread names directly, it costs about $29, and it gives you half-damper feel for the day you upgrade to a keyboard that can read it, without paying Roland money now.
If your keyboard is strictly a switch input, save the money and get the M-Audio SP-2. Its polarity switch and rubber non-slip pads do the whole job for about $25, and the on/off limitation is not a limitation if your gear cannot use continuous sustain anyway. Go with the Roland DP-10 only if you already own or are buying a half-damper-capable keyboard and want the closest feel to an acoustic piano's pedal, per the thread's own top recommendation. One thing worth separating out: the M-Audio EX-P is a different pedal for a different job, an expression pedal for continuously variable controls like volume or filter sweep, not a sustain pedal, so do not buy it expecting sustain.
Basis: r/piano's "Recommendations for a sustain pedal?" thread (post 1e5n5s3, July 2024), cross-checked against Amazon rating counts and prices as of August 2026. Specs are the manufacturers'. Ratings score merit with price left out, so the premium pick sits highest and the tier is where a pick sits on price, not how good it is. We track listings and prices; we have not hands-on tested these.