Of the three you list, the 4" Voyager Vaquero has been discontinued, so I'd say grab one now if you want one (grab a serrated and non-serrated if you can). The Voyager clip and tantos are half serrated, and to be honest I prefer a knife to be either fully serrated, or full plain edge, combo edge doesn't really work for me. I only have the plain edge Talwars, but they have a needle sharp point, I can imagine them being very slicey with Cold Steel's serrations, and they have the wave feature for quick opening from the pocket.
I do have the serrated 4" Hold Out. I'm fairly sure that the Hold Outs are the lightest of Cold Steel's knives in any particular size, the Hold Out 1 is lighter than any of the other CS mega-folders I own. I'm not sure but I think it is being discontinued too, so you can get it for about half the price of the plain edge version. I did get the IIIs too, but they feel a bit small in my hands.