Here's a selection of US WW2 armour from Sandsmodels. I think these models go very well with 28mm and I've included Artizandesigns figures for scale comparison. The vehicles are multipart resin kits, casting quality is very good with a couple of airbubbles which can easilly be filled. Turrets are moveable, small parts like guns and sometimes wheels are cast metal.
The vehicels come without any stowage which I like because you can add all the little stuff to personalise your vehilces to your liking. Sands sells extra stowage packs to go with the models or you can add stuff from the bitsbox. If you plan to get a M3 you'll need the stowage set to get the side racks and the stowage added at the rear of the vehicles.

M8 Greyhound and Jeep
M10 Tank Destroyer
M3A1 Halftrack
M8 Greyhound