Ah yes, our "Favorite PW engine" question! We always enjoy that one.
As for me, still the same answer: The 736 Berk with the die cast metal trailing truck. To me, Lionel really knocked it out of the park for a toy train: Handsome proportions. Wonderful "bulk", a good looking wheel arrangement, and more. What's NOT to like?
Lionel's Berk is the continual Siren Song to me in regards to me dabbling with PW again.
I also like other PW engines... but you asked which was our favorite "ENGINE" (singular), so I'm sticking to a singular answer.
Andre