Alas, I think Old Glory are the only game in town for mounted US Cavalry, if you exclude the truly execrable ex-Oupost 25mm range, now with Badger Games in the US.
It’s a great pity that Brigade Games never made mounted versions of their Paul Hicks sculpted dismounted cavalry. It’s about the only thing that’s put me off doing the period. I’ve even looked into how much work/pain would be involved in converting the Perry ACW cavalry.
That said the OG figures seem to be one of their better ranges, less gurning acrobats but still with the attendant problems of some misshapen and undersized equipment.