In all honesty, Zelda's recovery loses out to Sheik's.
If Sheik and Zelda double jump + Up B, Sheik actually goes higher than Zelda does. Test this out for yourself.
With that in mind, realize that Sheik's double jump > Zelda's in terms of distance, Sheik falls faster than Zelda does, and Sheik's Up B distance is somewhere around 2/3rds of Zelda's Up B. In terms of distance traveled, Sheik is a lot closer to Zelda than people think. However, there's more to the story.
Sheik's Up B start-up grants invincibility even before Sheik actually disappears. Then, on top of that, upon disappearing there's a powerful explosion. The OP should know just as well as I do that when you combine a powerful attack with invincibility frames, you get a very, very good and safe Up B move as far as start-up goes (see the beginning of Ness's of PKT2 and Marth's Dolphin Slash for similar examples of hard-hitting + cannot be stopped Up Bs). Zelda's, on the other hand, only gives a hitbox. No invincibility. This is a problem because the start-up does a mere 4% and can be pretty much cut through by most aerials. It doesn't even protect her whole body! The start-up time is roughly the same as Sheik's, but it is much unsafer and the attack sucks.
Then they travel... Zelda wins in distance.
Then they reappear. Zelda gets a hitbox and Sheik gets a strong wind effect. Now, as far as edgehogging goes, Zelda's wins because she can knock off edgehoggers. That said, edgehogging either one is still relatively simple because they travel from point A to point B without a hitbox, so as long as you're not vulnerable at the end of Point B for Zelda, there's nothing she can do to you. Zelda gets an advantage for the edgehoggers, but...
... what if they have to land somewhere above the stage or on the stage? Long-story short, both can be shielded, and it's a matter of who gains control faster. Sheik's wind effect is larger, though. Also, Sheik falls faster than Zelda does, so if they have to warp in the air, Sheik will hit the ground first and will therefore gain control faster like that. As for who gains control fastest if they warp into the stage (like just warping down), I dunno if there's a difference in speed between the two... but yeah, I say that Sheik and Zelda are around even in terms of Up B...
... then you take into account the fact that Sheik can dair to get down from the air quickly, can use her neutral B to attack those from a distance on the stage, in the air, or on the ledge (without going into freefall!) and has a good tether, and you can see that Sheik is the clear winner of recovery between those two.
I don't know how you can edit the list for just those two, considering there are other characters between them, but Sheik > Zelda, always.