[MaskedRiderAsakura]

Depends on which time period we're talking about.

Showa: Black

Early Heisei: Agito

Mid-Heisei: Den-O or Decade (yes, I know, we all hate Decade, but it's hard to deny that both he and Den-O have become the 'faces' of this whole era, if only because they're the two Riders that have made the most noteworthy appearances after their shows ended).

Neo/Later Heisei: W. Slightly edges over OOOs just because W is the one that set the formula for later shows (minus Gaim, which, while probably being the best written show in this entire era, is too much of a deviation from the rest of the franchise).