List websites or county assessor office for leads?

Hey Guys,

I am trying to figure out what makes more sense. Either going with a list from one of the many sites or doing my own work in the county assessor office. I once find a great thread taking about leads without MLS access but cant seem to find it again. Back to the origanal post, it seems a lot of people use the list's, that doesn't dilute the leads that will turn in to deals?