Simon Cowell has whittled down his pick for a new host on "America's Got Talent" to just 3 guys one of whom is Marlon Wayans ... TMZ has learned.

Production sources tell us 'AGT' brass is zeroing on Wayans and 2 other comedians to replace Nick Cannon. The other guys are Tone Bell and Brandon Mychal Smith.

Wayans is obviously the big name here ... but we're told the 2 others have just as much of a chance to land the new gig considering their acting and comedy chops.

Bell is a stand-up and actor who's worked on shows like "The Flash," "Truth Be Told," "Chelsea Lately," and "Key and Peele." He's also made appearances on "Late Late Show with Craig Ferguson" and "Comedy Knockout."

Brandon Mychal Smith is a straight up Disney kid, who starred in shows like "That's So Raven," "So Random!" and Disney movies "Starstruck" and "Let It Shine." He also played Little Richard in the James Brown biopic "Get On Up."

And of course, there's Wayans -- who's been in TONS of movies and shows. He's even got NBC hosting experience for their show "I Can Do That" ... so he might have this in the bag.

We're told Simon still needs to meet with the 3 prospects to really see who'd be a good fit. He could even scrap them altogether, but for now ... these are his top options.