Maybe there is more information somewhere so forgive me if I missed it. However, the best sort of crimp would, from my perspective, depend upon what firearm you are loading for.
My .45-70 is an H&R BC rifle and, for best results from it, usually with cast bullets, I like the Lyman taper crimp die designed for the caliber. It provides good neck adhesion and should do just as well, I'd think for most firearms other than those with tubular magazines. However, the Lee standard seat and crimp die, utilized as described by the gentleman above, should perform very well for you.
I'll belabor one point made though. There are two types of Lee Factory Crimp Die and, I think, the .45-70, having a slight taper rather than being straight walled, uses the collet type of LFCD rathen than the often praised and just as often maligned "straight-walled" type that is often mentioned in discussions of more common straight walled handgun cartridges.
stuffit