The Lord of the Rings Strategy Battle Game.
It's a good one that you should be able to find cheap at used game/book stores these days. It has enough profiles to fit pretty much any army, includes magic, and has good/solid rules for fighting inside buildings and cities. I've used it for light-magic Viking-based skirmishing, and for various other skirmishing not specific to Middle-earth.
The rules themselves are technically simply but tactically deep. It's likely the best game GW ever made (although I haven't read the Sigmar rules).
Thanks
n.