A tire compound will always grab better on the road if it is slick, no tread. A tire with awful non-grippy rubber will still be better in the rain than a knobby version of the same awful rubber, because more of it will be in contact with the ground (vs knobs lifting parts of the tire off the road).

What you would really want to be safe in the rain (and on things that get wet in the rain like manhole covers, traintracks, thermoplastic street markings), is good tire compound. And then yeah tires that put as much of that good compound in contact with the road as feasible.

I have ridden slick tires with awful compound that I would trust less in the rain than treaded tires with better compound. There's usually a price difference there.