I would never recommend Seedsigner despite the fact that it is AirGapped.
But SpecterDYI is great (the touch screen is best feature)
Discussion
Both are great devices. But of course you don't get a ncie touchdisplay with SeedSigner.
That's why I like Specter a bit more as well. And because of the Secure Chip option. But their should be such a option for seedsigner now as well.
But SeedSigner is good for budget solutions ^^