Unbound is probably more featureful (especially when it comes to DNSSEC, which, I mean, again, for what that's worth to you), but sdns is written in Golang. Unbound is written in C and has had at least one memory corruption vulnerability reported.

I'm definitely a fan of go over C. I was really happy with unbound as a local resolver for a good long time, but then started having DNS issues that would be cleared up by restarting unbound.