I have had the opportunity to run examples of each. The last was a two truck I was graciously allowed to run a few years back (I can't mention names).I want to elicit opinons from other enginemen, and hear what THEY liked. I will editorialize a little (I can't help myself).
Baldwin - The biggest. They were the "GM" and their engines were the "Chevies", not the best or the fanciest, but they sure could take the punishment. I worked a lot of Baldwins and my respect for them as machinery somehow makes me proud of them in a patriotic way. SOme roads, like the ATSF ordered (mostly) Baldwins their entire corporate history. The narrow gauges of America liked Baldwin because of their "no order too big, too small, or too specialized" corporate policy.
American Locomotive. This company was the product of a 1900 consolidation of a number of smaller builders. The dominant builder, Schenectady, was the the benefactor, as, one by one the smaller builders closed. Some would compare Alco as the "Studebaker" of the builders. They were capable of great engines, but not always. Some detractors say they didn't have the "finish" or "quality" of Baldwin or Lima. However, "heavy hitters" like the UP ordered a lot of Alcos, culminating with engines like the 800 series 4-8-4s ,that were capable of 90 mph speeds for HOURS! The three Alcos I ran were good locomotives (473,476,478), but that is all I have as experience with this builder.
Lima Locomotiv4e and Machine CO.
A lot of locomotive historians call this the "Cadillac" of the engine builders.The conundrum is that they built that reputation on the Shay patent. Shays indeed enjoyed an excellent reputation. A testament is how many are still operating. This builder hit its stride near the end of steam, with its "superpower" locomotives. Thgey sold a lot of them, wit the most famous being the GS class of 4-8-4 on the SP.
American-made locomotives were like its automobiles- sturdy and built for distance and abuse. Builders of the day told railroads their engines were good for thirty years. It's a fine testament that some engines far older than that still run.
The discussion is open- is there a difference among builders?