1/35 scale is the most popular scale for armor followed by 1/72 scale. 1/72 scale and 1/76 scale (often referred to as "Braille Scale") is very well detailed depending on age of the kit and manufacturer.
That scale lends itself to large scale dioramas that would be impossible to replicate in 1/35 scale unless you dedicated your garage to the dio. The scale is popular with wargamers, again because of the size.
Previously, wargaming armor was very simple and robust due to the fact that they were constantly handled. Scale modelers used the wargame armor to kit bash with regullar models to get a greater variety of more detailed scale models.
The 1/72 scale modelers and 1/72 scale wargamers have started to combine. Italeri has released several kits that include simplified parts for wargamers as well as detailed parts for modelers. The first two kits in this series are the DUKW amphibious cargo truck and the M8 armored car. Two very nice kits that have optional simplified (one piece) suspension or regular detailed suspension.
Here is a picture of the photo etch I use with the 1/72 scale armor I build. Note the penny in the photo: