What's the best format to export to?
That depends on the output use.
PNG was designed for the web as a GIF file type replacement and was not developed for the production of professional quality prints.
Which is why PNG does not support non-RGB color spaces.
Humans cannot see the minute differences between a print made of an image from a JPEG file and a TIFF file. To be printed both file types need to have an 8-bit color depth.
While TIFF can be saved as a layered file - JPEG can't, so TIFF is often used for commercial images so an advertising agency's art department can edit the file by layer to suit their publication needs.
TIFF files, even when flattened so they have no layers, are many times larger than JPEG files.
Many online print labs don't accept TIFF files by dint of their many times larger file size as a means to most efficiently use their image file storage space.
The bottom line is that different file types have different uses, so there is no one-size-fits-all answer.
Use the file type appropriate to the image use.
DNG is a Raw file type as is NEF, CR2, CRW, ARI, DRF, FFF, RW1, RW2, RWZ, yada, yada, yada.
DNG is an open source file type while most other Raw file types (there are over 100) are proprietary.
Many digital cameras use DNG as their native Raw file type.