Logic-is-your-friend said:
My vote goes to Claude Criquielion. I wonder how many (non-Belgian) guys here know him. People remember his "lost" World Championship, when Bauer crashed him into the fences and Fondriest who was losing the sprint badly, finished first.
But many have forgotten he was actually World Champion before that in 1984. Even in Belgium, people remember him as a classics rider (winning Ronde Van Vlaanderen, Flèche Wallonne x2, Clasica San Sebastian, Brabantse Pijl, WC, BC, as well as finishing on the podium of Liège Bastogne Liège a bunch of times). But he also managed to finish in the top 10 of the Tour de France 5 times! Best result was 5th place in 1986. When i look at Benoot, i see some Criquielion in him. Don't know if he'll ever fill the shoes, but just like Criquielion, he 's a very talented all-rounder, that can do cobbles, climbs, and races with a lot of heart.
Well I'm Danish, born in '72 and Claude Criquielion was my biggest and sole idol during the entire 80ies and start 90ies. For me Criquielion is a billion memories more than just the faulty '88 Worlds finale in Ronse. If one asked me about unluck for Criquielion, I would immediately think of how Moreno Argentin "stole" the 1991 Liége-Bastogne-Liége just in front of Criquielions nose. My good memories with Claude cannot be compressed in a single thread answer here, fortunately.
But I remember in start 90ies ppl a bit younger than me just referred "Creqelæon" to the one that lost his WC because of Bauer. Not the first time history has been "rewritten" by newer generations.
Just like the OP, I would put Jan Raas at the top of the "forgotten heroes" list.
Edit: My profile name could just as well be "Criquielion-Fan", but Zoetemelk is an older story for me, back to my first memories as a child