The usual trade-offs apply. Do you need good puncture protection? Long tread life? Low rolling resistance?

I'm using Panaracer Pari Motos. They're very inexpensive and very supple, but they have poor puncture protection and very short tread life. If you're willing to give up some speed and comfort for better puncture protection, there's also a gravel version of the Pari Motos.

I'm told the more expensive René Herse tires are more than worth their cost, but I've been avoiding them because I don't need that kind of addiction.