It's not really a fair comparison because Voat has been marketed on Reddit far more than Snapzu is. I have seen Voat.co being linked perhaps a dozen times, whereas I have only seen 2 mentions of snapzu - of which both were in a list that included voat and other alternatives. The fact that Snapzu uses an invite only system also helps a lot: teamsnapzu said that without that the site would be crushed within seconds.