His horcruxes could have been made out of just about anything, but he chose the objects he housed them in very carefully. How important were the victims other than being souls? In other words, did it matter who he killed to make his horcruxes?
Yes and no.
No, the Horcrux spell and ritual didn't require a specific person to be killed in order to make a Horcrux -- it could be anyone, as evidenced by Voldemort's killing of a Muggle tramp (also called an Albanian peasant by some) to create one of the Horcruxes.
That said, I think to Voldemort, yes, who he killed was significant in the process of making a Horcrux. Mainly I'm thinking of Tom Riddle Sr and Voldemort's Riddle grandparents, whom he specifically hunted down, killed, and then made a Horcrux (the Peverell ring/resurrection stone, IIRC). One might argue that the murder of Hepzibah Smith may have been important to Tom Riddle, as she was rich and from a long-established wizarding family, and owned the Slytherin locket and the Hufflepuff cup to boot.
So I say that no it technically didn't matter who Voldemort murdered in order to create a Horcrux, but, yes, in certain instances he may have had personal preferences for certain victims.