No, the steerer tube is threaded.

As for "the very best" frame, that's merely a matter of opinion. The finest frames, of course, were made by low production makers, and we wouldn't have heard of most of them. Alex Singer and René Herse are well regarded here on bikeforums, but I'm sure there were others in that league.

I'm actually sorry the French gave in to English threading and diameters. It makes perfect sense, of course, but French was based on the metric system.