The GMC CCKW

CCKW would be my choice. Many are opting for the M-Series Multifuel, as they can just drive it straight to a show with a truck that needs little.
Some things to consider;

Can you drive a truck?
Do have mechanical experience, and the heavy tools needed to maintain a larger truck?
Have you got the physique and tools to change a heavy tire and wheel?
Are you familiar with all of the components tha make up your truck, and their limits?
Although the trucks are made stronger than a Jeep, they also break easier if abused.
The Army has away to impress drivers not to do foolish tricks with a vehicle.
If opting for a Multifuel, a poor choice if you have no large bank account, do you understand there are things under the hood that can kill or maim you for life. The components are expensive and heavy. Injector return lines damage easy when stepped on and the fittings are not hardware store items. The fuel pumps have a habit of failing after long periods of storage, Average price is $400.00+
Engine repairs are not for the novice, rebuilds run from $6,000 to $12,000, and most will give the truck away before doing that.
Although a recent Army vehicle, many new replacement parts are in short supply, due to the Army using these 20 years longer than they anticipated.
As for the best choice of M-35 Series, the original gasoline powered ones atr more reliable and cheaper to own, they actually have more pep in some instances. The gas powered M-Series have been gone from inventory for 25 years and are scarce.

Stick with the CCKW, they are more resaleable.

A real fun all around truck and the most practical is the M-37, they ride nice, and in the hands of an owner with mechanical skills, are very reliable. I have two.
They are a mixture of WWII technology, and ultimate in army comfort as far as military ergonomics are concerned.

If you do buy that Army Truck, plan to have it trailered home, most have not had recent maintenance and may need repairs or good tune up and service before you get home.

Remember, all the Army Driver is expected to do, is to drive safely, keep the truck clean, and do the grease and oil changes. The Motor Pool does all the other maintenance. You will not have that luxury, and will have to buy tools and get help, or take it to a $75.00 an hour shop that will run up a bill just familiarizing themselves with a Military truck. Seals and U-Joints will be familiar, but all else requires technique different than doand Peterbilts.
The articles in MV and Army Motors are nice to read but there is a lot more to at than reading about it.