A couple of days ago I came across another manufacturer that does Spanish American War minis in 28mm, Tiger Miniatures. They look like they have a lot of character and are well sculpted, plus they actually have mounted cavalry miniatures (something that isn't seen often for The Roughriders, oddly enough). I emailed their U.S. distributor, Recreational Conflict, and asked how they measured up to Old Glory Miniatures and they sent me an image with a size comparison.
(1st from the right is Old Glory, Copplestone, Tiger Miniatures, Wargames Foundry)
In addition to the Roughrides, they also have some nice German Colonials as well! If you get the chance you really should check them out.