[llamabeast]

The cream of the crop to my mind are (and there is some bias in including my own here but I'm very proud of it):

Skaven by Sombre
Arga Dis by Sombre
Tomb Kings by me

The Skaven are derivative of the Warhammer nation, but it is _so_ worth it, they are awesome. My Tomb Kings are inspired by the Warhammer nation of the same name, but are not really close to it at all. Most of the inspiration comes from Egyptian stuff (with a few obviously-Warhammery exceptions). Arga Dis, so far as I know, is completely original.

Also normally late-age but fitting fine in middle age are:
Ulm Reborn by Sombre
Vaettiheim by Sombre

Finally, one I haven't tested closely but looks good is Alugra, by Burnsaber.

These are completely subjective opinions, but these are the ones I think are really awesome and get excited about. As you can tell, I'm a fan of Sombre's mods. I'm not thinking super clearly at the moment though (should be in bed), so apologies if I've forgotten anything obvious.