Dixon's Dahomey are an oddity. The figures range from small (25mm) to large (near 30mm). I'd say they'd scale in well with just about any of the companies mentioned. See photo:

From left to right: A cat, Copplestone, Perry, Eureka, Dixon (one of the larger figures in the range)
Foundry are the same scale as Perry/Eureka. I wouldn't mix these three with Copplestone, though, as this photo demonstrates.
Hope this helps.