GZG's the only one I can think of, though I'm not sure he does/did the 15mm ones.
They were from the Dirtside II/Future Wars range, and they made tanks in 25mm scale, and 6mm scale. Actually the latter - Future Wars tank - Model #T-04, I think, based upon the photo.
I suppose it is possible he made them in 15mm too, since I think that was his first range, before he started making them in 6mm and 25mm scale, back in the 1980s, or so.
I forget the name of the model, but it was a very nice looking tank, with an elongated, octagonal shaped hull, and turret, and nice looking main gun.
Not sure if he did IFVs and APCs in 25mm, but imagine at least a few.
He sold off the resin range a while back, and the name of the new owner escapes me, but they are/were in production again, last I checked.
Anyone have a photo of the Dirtside, DSM minis, from #114 - #118?
If so, I'd love to see those.
The catalog image I have cuts off the upper right hand corner for these. See attached photo from Jon's 6mm GZG ranges.