If you want museum quality, you can't get better than Micro-Metakit. Multiple cylinder (i.e. those other than 2 cylinder) locomotives have working gear, etc. Fine, fine detail.
Some of the Trix Fine Art and early Brawa brass items were manufactured by Micro-Metakit - Brawa's King Ludwig II's train.
Lemaco is the best of the triumvirate that is located in the Lausanne area of Switzerland. Metropolitan and Fulgurex are the other two. Metropolitan is out of business.
DHL, NMJ, Günther, M + F (Merker + Fischer), Westmodel (aka Bachman-Westmodel), & Gerrard should also not be overlooked.
Several of the manufacturers also had kits of their locos and rolling stock available. M + F (Merker + Fischer), Günther, Modeloco (pewter instead of some brass parts), Weinert, Westmodel, & Gerrard are a few examples.
I have probably missed several, but I am sure someone will chime in with more....