Tough call! So many clustered at the top for me. But if selecting one, it would have to be the Wacker. A very close second is shared by five #13 Fillys as well as an Engstron from you Sham. I have some nice edge polishing stuff en route to me, so after some work this weekend that lineup may change some.
I suspect that when considering smoothness, (at least for me) the factors that make all the difference seem to be (1) a good honing and then being polished using CrOxide and (2) something 6/8 or wider with the grind being half hollow to full wedge (most full hollow grinds are just not very smooth n this face).