Since you are talking handguns, I would say Unique if you are going to cast, 2400 if you shoot mostly jacketed.
In handguns I use cast mostly, and would use about 5.5 grs unique in a 357 and 158 gr, about 8.5 or so in a 44 with a 240gr. My rifle loads are 14 gr of 2400 and 158gr in a 357, and 23.5 gr of 2400 and a 200gr JHP in a 44. They will work in a good mag pistol, but I do not shoot heavy pistol loads anymore. I did use the 44 load in a Ruger superblackhawk hunter in the past with good results. Either powder can do it all adequately, but depending on the bulk of your shooting, one will slightly edge the other.