As far as I know, you can't compare their security features since SeedSigner doesn't even store your seed as it is stateless so it doesn't retain any information. I know that Coldcard has great security features compared to other wallets, but it still requires some level of trust.
Discussion
I think there’s an understated risk with that approach. You’re handling private key material every time you need to use the device. I appreciate the nuanced discussion. I hope people get value from this.