peach has advantage for sure.
She can float right in between falco's immediate laser heights, then being safe on his shield coming down to that is really good. GC on some stages is good as well (DL, FD, and FoD sometimes). D-smash is gay and gimps falco pretty easily, plus her amazing and simple edgeguards on falco. D-smash hitting falco multiple times at low percents is gay, with potential tech chase setup. She also has beastly priority on falco (FALCO!!!).
Falco's side of the matchup, is that he may be able to stuff her out of her float approach, if he can avoid trading/getting out-prioritized. His lasering is good for pressuring her when she's on the ground at a distance, otherwise he will just get dash-attacked by the ***** and pressured himself. He has decent combos at low percent, but then he sometimes has trouble getting kills at higher percents, until he can kill her with a b-air (unless he somehow lands a d-tilt or f-smash). He can also edgeguard peach really well if she is low enough for you to bring her down with lasers, but sometimes it's really impossible to get an edgeguard when she's knocked off the stage. Also, falco's d-air -> f-smash tech chase is gay. Falco can also get some n-air -> d-air kills at mid-high percent.