Hardest rhythm game song (still playable)

What would you guys say is the hardest mildly playable song in rhythm game (customs included). These include "Valkyrie Dimension" Challenge (DDR X2), "Paradoxx" D28 (Pump it Up), "Egoism 440" Challenge, "Soulless 6" (Exilelord's Guitar Hero custom), "Over the Period" Challenge, or something else? This only includes single player songs (except in the Pump It Up example).

"Valkyrie Dimension" Challenge
https://www.youtube.com/watch?v=Hromx6HeN_w

"Egoism 440" Challenge
https://www.youtube.com/watch?v=l7Vx5FvX7-E

"Over the Period" Challenge
https://www.youtube.com/watch?v=YKQX0kgiNtI

"Soulless 6" (Exilelord). It's a Guitar Hero 3 custom originally but even the bots can't FC parts of this.
https://www.youtube.com/watch?v=5gMspNaL2S0

"Paradoxx" (D28)
https://www.youtube.com/watch?v=rquLGNHuxvI

"Bemera" D28
https://www.youtube.com/watch?v=SExxVYHfMGs

"Mendes" Black Another. It's crazy even by Beatmania IDDX standards.
https://www.youtube.com/watch?v=Y57snv0G0TI

"Operation Ground and Pound" by Dragonforce Expert (Rock band 3 chart).
https://www.youtube.com/watch?v=jIS52CW3Gdg


Maybe something else ...