I see in the roadmap for Designer that a Mesh Warp tool is on the way and know there is such a tool in Photo already, but the feature in both Illustrator and Photoshop, that I use the most, that is missing in the Affinity apps is the ability to apply different shape transformations: wave, arch, circular arch, arch top, arch bottom, etc. to live typefaces and to edit the amount and shape of these transformations at any time. In Photoshop, for instance, I can create a type object, apply various effects to it, then arch it, but later come back and edit kerning, the actual text and even the typeface. This feature is also available in Illustrator.
This ability is the what I need most to fully replace Photoshop and Illustrator for my art creation purposes, which is my goal. I'd like Affinity Designer and Photo to be my full permanent replacements for Adobe apps. They are super close and I am using them for most things already, but the Live Type warping tool would really seal the deal.