Id recommend either an Atlas Gold locomotive or a Broadway Blueline. For the Atlas, youll need the Quantam Controller to activate sounds, and for the Broadway youll need their Analog Controller to activate the sounds. The Blueline is a little cheaper at about $115-135, whereas the Atlas Gold is usually between $145-225. Tack on an extra $30 for the analog controller for each.
As far as which one is better--its endlessly debateable. The Broadway Blueline is a very nice engine and a good puller, but youll be hard pressed to find someone who doesnt fall in love with an Atlas Gold. Very smooth drivetrain, great details, good pulling power, nice sound.