Depends on which anime fighters and which american superheroes. Granted, there are some american anime fighters and japanese superheroes out there . . .
Going by the strongest incarnations of each character . . .
The strongest incarnation of Superman can maybe give even Zeno-sama a good fight, so Superman without a doubt.
Vegeta is too fast, too strong as has way too much destructive capacity. Even the adamantium bones gets reduced to ashes.
Buu turns Hulk into candy or even adsorbs him.
Even Demon King Piccolo would stomp.
Even chapter 1 Naruto would stomp.
There are a lot of Van Hellsings out there. Going by the one with actual super natural abilities, he stomps.
Not remotely a good matchup. Rock Lee can't even break lightspeed (or even come close to it), much less keep up with the Flash.
Batman is smarter than Inuyasha and has tons of nasty gadgets that would screw up his heightened sense of smell enough to paralyze him (which we've seen happen in Inuyasha) and dispatch him afterwards.
The strongest version of Green Lantern could chuck Sasuke into a black hole before he even knew the fight started.
The strongest version of Wonder Woman has 18 beat at everything except energy projection.
How is this even a matchup? Krillin lolstomp.
Planet busting Yusuke solos. Hypersonic Hiei solos. Hax plants Kurama solos. Dimension cutting Kuwabara solos. Together, this isn't even a match.
Kakashi kamuis Scott's head into another dimension before Scott can even react.
Superhuman strength Sakura punches Elektra's head clean off then kills herself upon realizing how sh-tty a character she is due to the lazy author that created her.
Even if it's Cosmic Spidy, Island busting hypersonic Luffy murders the webhead before the webhead even knows this ridiculous matchup has even started.
First a whole tone of people debunked the superman vs goku 1 and 2 from death battle plus combat speed travel speed are totally different things and superman would lose to ssj4 goku and Kaioken x10 ssb goku and
vegeta can just use a blast that burn wolverine body and cell cause wolverine can't fight at light speeds so he is out
krillion can beat daredevil cause krillion can fight at the speed of light and daredevil never reacted or dodged anything faster or at speed of light so krillion wins i think you the rest.