Fave Steam Engine(s)

[roadkill]

Hmmmm...

NYC S1a 4-8-4
C&O K4 2-8-4
C&O H8/VGN "Blue Ridge" 2-6-6-6
N&W A 2-6-6-4
B&O EM1 2-8-8-4
WM I-2 2-10-0
PRR I1 2-10-0
PRR J1/J1a 2-10-4
NYC L2 & L3 4-8-2
PRR M1a/M1b 4-8-2

[wmfred]

I would have to say the Western Maryland Big 6 Shay & the 0-4-0 Reading Camelback.

[danraitz]

That would be the Great Northern O8 class 2-8-2.
www.gngoat.org/gn_steam_17.jpg

[stevenhong]

Any Mallet with 12 or more drivers, with some exceptions, as well as almost any 10-driver locos