My opinion is that the 'out in the field/in service' look is the most interesting...
We all know what a spotless Jeep/a pristine Dodge/an Immaculate Lightweight Landy looks like...
But for my money the research, imagination and effort in putting a vehicle into a historical context (this is how it looked at the Bulge or in the Bocage or Falklands or whatever) shows a greater appreciation of the purpose of the machine and the attitude of the men who used them.
They weren't cherished or kept clean and in many cases actively disliked by the men who had to use them!
However the 'judging' of military vehicles is a bit of a grey area as they mostly seem to be judged on the criteria applied to the restoration of vintage cars. How Shiny? How Straight? How perfect the Paint? One set of rules applied to a very different type of vehicle.
How for example would you pick out the best vehicle from a jeep and e-type and a Model T-Ford?
The original paint finish on a model T is shocking... sprayed in dusty sheds with very crude equipment... do you replicate that... or go for the perfect "35k Merecdes" finish?
Trim finish on older Jags could be crap but do you ever see that in restored ones? No
& a Jeep could've been transported on the open deck of a ship to to arrive at its destination stormlashed salted and beginning to rust already!
I've been to car shows and even taken part (never won though lol!)
but judges don't seem to like to see spent 30cal shells rolling about on the floor, crushed k ration boxes, webbing slung from any available protruberences... they just see mess!
"ooh lets pick the glossy shiny Landrover parked over mirrors so you can see there's no muck in the wheelarches"
go figure!