Ironclad are of course very nice. Sizewise, the only one of the range close to the GZG tank is Steam 1: Small Scout Tank. I have one of the £9.50 armoured cars and they're about 50% bigger than the GZG tank.
The Black Pyramid steamtanks are also very nice. Despite the names the Medium and Large landships are both very large compared to the Ironclad models. I have some pics on my blog, the first from when they were previewed at Britcon, showing off all the possible add-ons that were planned. The second is from my review of when I actually got hold of the basic models for myself.
Previewed at Britcon
http://axisofnaughtiness.blogspot.com/2011/08/my-tank-my-tank-is-fight.htmlHands on review
http://axisofnaughtiness.blogspot.com/2011/10/my-tank-has-armour-plate-to-save-me.htmlSince writing the above review, I've bought several packs of their add-ons and fitted the heavy landship with side-mounted gun sponsons and as suggested in the review, they really make the model come alive.
I'd recommend them if you're looking for a heavy, slab sided landship, but certainly not if you're looking to match the cuteness of the GZG/Eureka tank.
Dr V