What kind of steam engine shold I choose for a DRGW layout ?

The choice of a D&RGW locomotive depends on a lot of variables.

What scale are you running?  What is you planned minimum radius?  And how much are you willing to spend on a locomotive?

The two main scales with the most available D&RGW equipment are 1:22.5 and 1:20.3

1:22.5

LGB, Bachmann, USA, Aristo, and Hartland currently offer a wide arrange of equipment in 1:22.5 scale.  Prototypical D&RGW locomotives in this scale, however, are very few.  If you want to capture the modern narrow gauge era (1930's to 1960's), as most D&RGW modelers do, the only prototypical options are the Aristo-Craft C-16, and the Kiss K-36  The C-16 is very toy like and I would not recommend it, and it actually scales closer to 1:24.  The Kiss K-36 is impressive, but it's made of metal and costs a fortune.  Not really ideal for most layouts, and more of a museum or mantel piece.  LGB/Aster released a beautiful brass K-28 many years ago but this will also cost you plenty...with the current market value of a mint loco around $6,000.

So your options for prototypical locos become thinner in 1:22.5.  I run this scale.  So for mainline power I went with LGB moguls.  Although these are not even close to a prototype D&RGW loco, they look good, are very reliable, and can take the tightest of curves.  I had an older C&S mogul that I simply relettered for D&RGW.  Then I purchased a newer undecorated loco that I also lettered for D&RGW.  LGB currently produces a mogul factory painted and lettered for D&RGW in the bumblebee scheme and about a year ago in the standard black scheme.

Here is a photo of my two moguls:

1:20.3

If you go the 1:20.3 route your options are very good for prototypical locomotives.  Accucraft and Berlyn control the market right now, however Bachmann is supposedly going to offer a 1:20.3 K-27 in plastic.

Accucraft locos are the most reliable of the group but they tend to be finicky with your track.  They are huge and very heavy too.  You need a lot of open space and excellent track work to ensure these locos run properly and look right.  But apart from opperational issues, the biggest downside is the cost.  These are all priced well over $1,000 each.  If money is no option fantastic.  But I'm not ready to spend this much money on a loco that won't run as reliably as an LGB mogul.  Plus I'd be worried to leave them outside, even though I'd cover them.  And the large size bugs me for some reason.  They just look too big.

My advice

So if I were you I'd get some LGB moguls.  It's almost a standard for G scale.  And the reliability you get out of them is unsurpassed, at this point, by any other G scale maker.  and they look great pulling LGB, Aristo, USA, Bachmann and Hartland cars.  Be sure with Aristo and USA you avoid their modern 1:29 scale equipment.

BTW, glad you went to Rail Fest.  I was there.  Our layout was also featured on the layout tours for the Narrow Gauge Convention in Durango which occurred roughly the same week as Rail Fest.

If you are interested in seeing more photos of our G scale D&RGW layout click on the Snowshoe & San Juan link in my signature below.