The Coway Airmega 400S outperforms the Blueair Blue Pure 311i Max in raw CADR (350 cfm vs 300 cfm) and offers smart app integration, making it the stronger choice for large homes (RTINGS, Consumer Reports). However, the Blueair is quieter at low speeds (33 dB vs 33 dB min but peaks lower) and fits tighter spaces, so it remains a solid mid‑range option (RTINGS).