I'm not sold on Marth being harder than Falco, if at least because Marth's physics are far more ideal for Mario to work with when juggling and comboing him. You're not going to have many chances to get inside the range of either character, but getting inside Marth is significantly more rewarding since once you put him above you, he can't just spam D-air or shield at low percents the way Falco most likely will. The threat of Falco's D-air alone is likely going to force you to stale U-smash. Also Falco juggles Mario better than Marth does and doesn't really kill later with his aerials.
The main thing argument for saying Falco is easier is counterpicking him to Brinstar, which if he has a brain, he'll ban. Then he'll dominate you in new creative ways on whatever stage you're left to pick and hope he doesn't have specific knowledge of.
Oh also, landing a Jab on Marth is utterly amazing when it happens. Landing a Jab on Falco...you can link into Up-B I guess.