Depends where you're coming from in terms of interest I guess.
Most folk have a passion for a specific type of vehicle - which leads to finding and buying one. If it needs a lot of work then maybe the fun will really start, as spares for certain vehicles can be very difficult to locate. Often it is only the strong bond with the vehicle that keeps the owner going during what can be a long and frustrating search for parts. On the other hand some folk enjoy the spares challenge
I only mention this because if you are simply after a military vehicle to work on to fulfill your main enjoyment as a restorer, then it may be wise to select a vehicle for which parts are readily available - if not you may get disheartened and abandon it.
If you can specify your main interests (e.g. British / body or mechanical restoration / hunting difficult to source parts / making impossible to source parts ), then it may be easier for members to give the right advice?