Hi, I can't comment on the Wargames Factory Aztecs as I don't have any, but do have their Conquistadors. Height and build-wise they match quite well with the Eureka figures, but are a few mm smaller. They are smaller and less bulky than the Foundry Elizabethan Swashbuckler range but then I thought these latter chaps particularly well-fed! One thing about the Wargames Atlantic figures is that the heads seem quite small....or maybe metal heads are sculpted too big. In summary, I would mix plastics with the Eureka and Foundry metals despite the differences.
I must admit I don't like what I have seen of the Wargames Atlantic Aztecs. Way too "beefy" IMHO!