So Old Glory and Foundry mountain men/Cameron Mexicans+FFL mix in well. The Foundry Peons are a bit smaller but can still work with thin boosters. 1st Corps Mexican American war figures are about the same size as Artizan.
Dixon are smaller still and don't really work IMO, even with boosters.
From the left: Old Glory, Artizan, Northstar 1812, Foundry Mountain Man, Artizan