Personally my all time favorite is the Chrysler Astrodome dash but as those didn't appear until 1960 that doesn't apply here.
For the 50's I'd have to go with the 1957-58 Dodge dashes.
Dodge dash 2 by
M Patterson, on Flickr
Besides having a full set of gauge pods (that were actually pretty easy to read), the ash tray was kind of neat....rather than pull out it spun around.
While the 3 speed stick cars and two speed Powerflight cars had a conventional ignition switch, the switch on the Torqueflight equipped cars only had acc/off/run positions. To start the car you turned the switch to run and pushed in on the neutral button in the shifter pod.
The neatest part was the ribbon type speedometer with the red line that read off the speed.
dodge dash 1 by
M Patterson, on Flickr
I'd actually considered using that dash in place of the original un my 57 Plymouth (it would have been a bolt in).