If it were me, I like the 3-speed hub best of your listed choices. Automatix looks nice but 10mm OLD difference is pushing it IMHO, even with steel.

OK, going from memory here, but isn't there a SRAM S-RF5(W) with 111mm OLD? I seem to remember Brompton users going for this 5-speed hub because of the compatibility with existing Brommie rear triangles, which are 112mm OLD if I'm not mistaken.