I have both. The Foundry ones are pre-Great War (and that's what I bought them for). But they were still wearing that uniform at the outbreak of the war, so I quite happily use them.
The Brigade ones appear to be in a mix of the pre-war blue uniforms, with a couple of them in the transitional Khaki (with blue trousers) that came in during the war. None of them are wearing the late-war full khaki uniform.
I would say get the Brigade ones if you must choose between them, but I like the ragged filibustering look of some of the Foundry fellows, so I use them too.