Bill,
Info, not intended as a recommendation....
Scale closest to correct for 45mm (G gauge) track:
Standard gauge mainline 1:32. MTH and Accucraft make products in this scale. MDC made rolling stock in 1:32 as did Lionel.
note:
Defacto standard gauge especially for diesel is 1:29 scale. USA and Aristo manufacture in this scale.
1:29 and 1:32 don't look well together so unless you want to just run separate trains or don't care you should choose one or the other. Both make for nice standard gauge railroads and the too large size of 1:29 on 45 mm track really isn't very noticeable.
3 foot gauge (most common narrow gauge in US) 1:20.3 scale. Bachmann and Accucraft are main suppliers. None of the other scales look well with 1:20.3 scale. Bachmann sells what they call 20' cars in 1:20.3 but unless you are modeling Civil War era they definately don't look well with anything else in 1:20.3.
Earlier Bachmann and LGB (US configuration) represented primarily 3 foot gauge in 1:22.5 scale. Actually 45 mm track scales out to 42" gauge in 1:24. Also Delton (now produced mostly as Aristo's Heritage series) is 1:24 scale (nominal) as were USA's earlier wooden (plastic) cars. The 1:24 are almost identical in over all size to LGB and Bachmann 1:22 cars and go well together. Hartland (not Hartford) is also 1:24 but the cars are of a smaller size.
Meter Gauge 1:22.5 scale. LGB's European style offerings are pretty much to this scale.
Besides the above there are other manufacturers of kits and limited models in these scales, primarily in 1:32 and 1:20.3. These are either craftsman kits or pricier lines. Accucraft is moderately expensive and includes live steam as well as electric powered locos. I included them with the "thriftier" brands because they are a major player.
There are also numerous other scales operating on 45 mm track but they are primarily for the purists, kit bashers and scratch builders.
Hope this helps "unscramble" things a bit.
