. . . I come back, and you guys are talking about Yoshi's vs. D3 . . .
NO NO NO!
D3 can still chaingrab Marth on Yoshi's. Additionally, due to the slopes, you cannot safely aerial D3, because you'll ALWAYS slide into grab range. You can't edgeguard him properly, because he can upB against the wall and cancel it into the ground super low, so you have to shield, and he gets his jumps back. You also cannot knock him under the stage. Shy Guys are more likely to mess you up than him (IT DOES HAPPEN). It's hard to get back on the stage from the ledge due to the little slopes that block you from properly using all your options. The platform in the middle is NOT good for Marth, unlike other platforms. It's just too high to be really useful, while it gives D3 options in some situations. The only things I like about this stage are that you can use the middle platform for mindgames when trying to land after whiffing an UpB and that you can line up certain aerials better due to the wall, and recover very reliably. However, you can't stage spike people, so it's a negated bonus.
Don't take D3 here, lol. D3 cannot ban Lylat and Battlefield, so you're definitely taking him to one of those. Smashville is awesome. Though the platform helps his recovery more than you, it's definitely a decent platform if you know how to platform cancel well. It's short, so CG isn't a huge issue. Awesome stage-spikes. D3 also can't camp here very well, and Marth pressures SO awesome on this stage. Stage Spiking is super duper easy, and this ledge just yells "Marth, please recover". It's a simple stage, and Marth likes it a lot.
All the stages Marth likes, D3 likes too for other reasons. I have NO problems taking a D3 to Castle Siege, Rainbow Cruise, or Delfino, but I wouldn't recommend any of them unless you're super comfortable. Battleship Halberd is supposedly in his favor, but I always seem to **** there. I think it's good for Marth. It's usually the one counter-pick that's an upset and I end up winning. Do not play the Frigate game with D3 unless you're absolutely amazing at that stage. His UpB sucks there, but yours sucks worse. Poke Stad is meh, if you know how to camp and don't get ***** by dumb infinites like a loser.
Really, I'd go with Brinstar. The platforms here are good for Marth. LEARN THE SHINANIGANS THOUGH. D3 can auto ground his UpB on certain parts, but compared to how badly you can harass him, it doesn't matter. MBR, REMIND ME to start a discussion about Brinstar tricks. D3's Utilt kills well here, but he's fat, slow, and has no where to run. Just hop in the air and start harassing him with your speed. He can't Bair edgeguard you the same, because you've got more aerial movement, and a few tricks with your recovery options due to overhanging platforms, and the ability to rise through the stage. You can also K.O. D3 pretty early if you reserve tipper Nair or Fair (two Dancing Blades keeps the decay away), and hit him while he's far off the stage. He basically has Backthrow and Bair to work with. Your whole moveset is viable on this stage. Learn it and use it.
EDIT: I didn't mention Norfair, PS2, Japes, Corneria, or Luigi's, because those stages are usually banned in my region. We have a strict stage list.