My favs as respects to aesthetics, in order:
Flyer 30B
Flyer 18B
Lionel ZW
Lionel LW
To me the Flyer transformers jus kook beefy and what I imagined as a kid what real train controls looked like.
The ZW is just cool!
The looks of the LW are nostalgic to me as that is what I had as a kid