I'd be interested as a horn player to hear what the other horn players use and also what type of mouthpiece.
I have three horns, the main one I use is a Yamaha 668 which is a copy of the Kruspe and I find it very good for the work I do, orchestral, concert band and shows.
I also own a King Eroica which is a big bore very free blowing horn and also a single Bb Schenkelaars which has a stopping valve which is very handy for playing horn parts in E which are too hard to finger on the Bf/F horn.
The mouthpiece (out of about 30 that I own) I am using is a Tilz number 9 which is 14.5 mm wide. I have a Tilz number 11 also which is 18mm which I intend to try in the future when time permits.