I prefer DL to FD because Young Link has an incredible platform camping game that Samus can't really do all that much about. This is even more exaggerated by DL being a fairly large stage. Though it's easy to win the projectile game against Samus on FD, her missiles are a somewhat-effective form of horizontal stage control. On FD, you have to maneuver around her projectiles, which is kind of annoying because she can use them to get you in a place where you don't really want to be. Young Link's aerials help him land in case Samus tries to keep you in the air and punish you, but Samus has that nair and can gain a positional advantage.
That being said, jumping over a missile into bomb-dair at <100% for the kill is hilarious.
The main issue with DL is that Samus just doesn't die, but that's mitigated a little bit by a superior platform game that makes it far more difficult for her to control the stage.
Out-camping Samus is very powerful on DL because there's not much she can do about it. Her missiles don't hinder you all that much, and you can just throw lots of projectiles for days. It's really safe.
DL also grants Samus good mobility options because her wavelands are so good, but we still have great advantages in camping and avoiding pressure. I think that we get the better end of the stick here.
I find that playing a more aggressive YL against Samus is a little bit tricky because she has that dreaded nair and a fair combo game on him to boot. I prefer to take Samus to DL over FD because it's much easier to take a lot of defensive and campy options without being forced to do all that much all that often.
Overall, in my opinion, Pokemon > Battlefield > DL > FD > Yoshi's > Fountain
