Mark is one of the three sprinters to make a credible claim on being the GOAT (Darrigade/Cipollini are the other two), but I think it's pretty much over now.
Arguably a greater rider with a GT win, 2 WC and an all round classic rider (also in his best years a beast in TT's). But Maertens was the best sprinter
for just a few specific years, whereas Cipo and Maertens just stacked up multiple wins year after year. Just in absolute GT stage wins he isn't in the same category (but his average on the few GT's he rode is shocking). So even though the argument could be made I rank Mario and Mark higher as pure sprinters.
Then again, does Darrigade deserve to be in the running over Maertens? This is the perpetual problem with these kinds of lists... comparing era's and palmares is futile... and a lot of fun
So sure: Maertens/Cav/Cipo for the best three sprinters, followed by Darrigade and Alejet. *I wonder which superstar I'm forgetting *
The Cipo versus Cav is interesting. Cipo has an eyewatering amount of GT stage wins, but Cav has more TdF stage wins. That's partly by Cipo's choice as he couldn't be arsed to drag his body over the French cols (something he was more than capable of). I think I give the nod to Mark due to the TdF being the bigger event, but jeez.... so many stage wins by Mario is hard to dismiss... so I guess I pick Mario after al.... or.....ARRRRGH