Definitely the D&RGW! Long trains, spectacular scenery.My railroad is mostly D&RGW power and S.P.
The Little Railroad that Could
Jersey Central RR
BORN AND RAISED on the CNJ
Dad was ticket/ Freight agent
I was signal maintainer 68-74
Hmm...for me, it is a toss-up between the Santa Fe and Southern Pacific. I remember seeing quite a few SP units on the old Southern Pacific line that goes through Chico when I was younger. The last time I saw a unaltered SP unit (original bloody nose scheme with only a UP number patch) around my neck of the woods was back in 2007. Union Pacific now uses the old SP line and other than a rare KCS unit and the occasional Amtrak train (Coast Starlight), only UP units move through our area.
As for the Santa Fe, I always loved the warbonnet paint scheme they ran on their units, regardless if it was the blue/yellow or the classic red/yellow/silver warbonnet scheme. My first two HO locomotives I got (F3 and a GP unit) were painted in the classic warbonnet scheme and boy do I regret not getting to see more Santa Fe units in real life. Other than the occasional BNSF unit that passes through in a faded, beaten-up warbonnet scheme, I have not seen any unaltered Santa Fe units in real life (other than the ones preserved in museums).
The Merioneth and Llantisilly Railway Traction Company Limited. And the Chicago and North Western.