My choice would be the Lionel PowerHouse 180 bricks. Excellent fast electronic circuit breaker and very reasonably priced per watt of power. Any claimed advantages for smoke production to chopped wave transformers evaporates when they're set to full power, and pure sine wave is least likely to generate any electrical noise that may affect your trains, or even other electronics close by. For pure command operation, the PH180 is hard to beat. You might want a variable transformer for accessories, many of them are picky about the voltage range they run in.