From Software.
It would be interesting to see what they'd do with a 3D Castlevania. They know 3D level design, at least. IGA surely did not. And they know challenge. And atmosphere.
For 2D I'd say Yacht Club, for sure. Shovel Knight was brilliant in all its 8-bit glory, and I'd love to see them do a 16-bit (or even 32-bit) style Castlevania.
WayForward is too hit or miss for me, but when they get it right, it's soooo right. When it's wrong though, it's really mediocre.