Gravel tires I use currently (or recently):
Donnelly X'Plor MSO 40mm
Donnelly USH Strada 32mm
Panaracer Gravelking +32mm
Specialized Pathfinder Pro 38mm (42mm measured)
Vittoria Terreno Dry 38mm
Kenda Alluvium Pro 35mm
Kenda Alluvium Pro 40mm (43 mm measured)
Kenda Flintridge Pro 40mm (43 mm measured)
At the end of the day, I can say that I like them all. I stopped using the GK+ slicks only because I want some kind of tread for flat protection, plus I tend to wander off the beaten path alot. The Strada 32mm is my winter "road" tire for those times when all the gravel roads are snowed in. The Alluvium Pros are fast rolling tires that last forever, and they are decent in the rougher stuff. But, if I had to pick just one tire, it would be the Donnelly MSO 40mm. And, it was the first "gravel' tire I bought many years ago (before tubeless). The only problem with the Donnelly is that I have had a few over the years with a bad casing/wobbly treads. My shop has been good with replacing them, but they obviously have some kind of quality control issue (or too many long lunches at the pub).