Hi, i have built all 3 and found them all to be ok.The Tamiya Leopard is a super kit to build, i did mine out of the box which is a rarity for me. The Chally is not as good as the tamiya one but is cheaper, but looks good once you have got past all the unnecessary small parts like engine deck hinges, and the AS90 builds up nicely, although replacing the turret top basket for a PE one is a must.
I have built the Faun with a Panzerhaubitze 2000 as the load and i found both kits a joy to do, it is sat on a large base with a large tree and some bushes by a road and i will be adding a Mercedes G Wagon to it aswell.
I don`t have any suitable modern German army figures to go with them though.