I like Forged in Battle, Museum Miniatures and Cromarty for my Ancients. Although Xyston have some nice figures I have yet to buy from them.
Museums Z ranges are more or less metal miniatures cast from 3D print masters.
And a note regarding FiB, they are more the mid range of 15mm, but some of the range (like the late republican roman) I swear are larger then the rest of the range.