Since this is just for fun and the author wasn't really specific, I think including amateur stuff can't be avoided. But if someone ask me this question, I wouldn't used amateur stuff. Just stuff with an actual plot.
You might be saying the real "winner" being someone fucked 1000+ unique individuals on camera but so niche and amateur no one on here can remember her, is not interesting conversation for you? Hmm yeah... maybe maybe not.
Hmm yeah I already said about as much, the strong candidates mentioned so far are almost never appeared in my collection. Minor exception is Yumi Kazama, I think I remember many years ago she used to be young and hot, and I must have fapped to her more than once or twice. But even if the winner isn't someone can get me a hard-on, it's still interesting topic, who she is, what studio/label she appeared in, how many men did she fucked in her career. Probably a gangbang specialists, and many of the individual men in statistics had a JAV career was only a few minutes long.
If we put aside the "real" winner and chat about famous idols who fucked many men, not necessarily absolute numerical champ. A few idols had burst of incredibly high output, over 20 new (not compilation) titles per months, including more than 10 solo works per month. These bursts tend to burn out after 3-4 months, so a few iron-ladies had kept it up for more than 6 months... maybe a whole year.
Mio Kimijima 君島みお before she became mellow contract girl, she made porn for anyone, major and minor studios.
Almost exactly the same story for Eimi Fukada, but since about a year ago, she increased the non-porn components of her mix of activity (and income) so she's down to maybe 1-3 men (and many repeats) per month.
Ruka Inaba 稲場るか recently went on a rest phase, but she was on a huge number of covers for each month's new vids for over a year. Of course her career is still very very early. But in terms of number of different men fucked over a one year period, for a well known idol, she's up there.
Honoka Mihara 三原ほのか, recently retired, over a 6 years career, was very open to any genre and any studio. Not the most number of men for career, not the most men per month or year. But she would not say no to almost anything, so quite unique for a top idol.