I would highly recommend the Mikado Jr engines by Lionel. They made them with TMCC and they are pretty nicely detailed for the price. The sounds in them are great too. The only weak point is the smoke units. I managed to burn two out in mine but that could have been operator error (thought I had enough fluid in them though). I pulled a 25 car freight train with mine for about two hours at a show once and it was barely warm when I swapped it out. They're not scale but they look nice and mine doesn't seem to look out of place with my scale engines.
Here's a picture of mine. I've added a headlight visor and painted the headlight, marker lights, front smokebox supports and smokebox front handrail black. The supports were shiny metal and everything else was the same graphite color as the smokebox.
