FoD is easy to recover on as you mentioned. Also, it's narrow (easier to reach edges if you get juggled) but still has a big blastzone.
YS is similar to FoD but much smaller blastzone, but the platforms are better.
Both these stages' top platform is at a perfect height for our upB when we need to escape.
There are platforms or structures on all the transformations of PS to help us get back down. As you mentioned, the normal transformation's platforms are good for missiles, and the platforms are not at the edge for Marth to recover on. He has to land on stage or go for the ledge, so it's easier for us to edgeguard. Also, Samus doesn't get many vertical KOs, but Marth does in this match up.
PS is still very wide, so it can be hard to get down, and the platforms also means auto tippered Fsmash.