First off, after surfing 7 eBay pages of Marx transformers, I couldn't find an example of the 1859 transformer. Darn.
My take from the FWIW category:
Most Iconic: ZW (Screams "POSTWAR!".)
Most Railroady: KW
Most Nostalgic (for me): Allstate (Marx) #6030 HO Powerpack:
Received the above little power pack accompanying my Lindberg Lines HO set that my mom and dad purchased for me for Christmas 1962. Mine was soon missing a handle, too. MANY pleasant hours were whiled away watching my Lindberg B&O SW (and later my Tyco Santa Fe GP20) whir around the track pulling those fabulous looking Lindberg Lines rolling stock.