I'll jump in,
The first two because they are consistently excellent smokers.
1.Sasieni
2.Barling's
The next because he was the first pipemaker whose work I "collected"
3.Elliot Nachwalter, I have pipes from throughout his career.
4.W.O. Larsen, You have to know what you are looking at, the early shapes by Sven Knudsen and the pipes that show Former's influence. Also the pipes made by, or show the design influences of Tonni Nielsen and Teddy Knudsen.
5.Celius, In my opinion one of the most distinctive design aesthetics from that period of Danish pipe making.
6.Peter Brakner, if you have ever smoked a Brakner, you will know why.
7.Stanwell I really look for the early Ivarsson designed shapes.
8.Savinelli I don't think I've ever had a Savinelli that smoked badly.
9.E. Wilke You don't have to spend a fortune to find a great smoking estate pipe.
I'll stop here, but there really are a lot of great pipes to be found and enjoyed.