best classified script? Osclass or Hivepress?

go with what feels right to you, there is not a wrong choice

it really depends on how far you plan to push it. hivepress is easy to manage and feels safer if you already know wordpress.
osclass is clearly built for classifieds, but dealing with bugs and fixes gets old fast if you’re not technical.
i’ve seen a lot of projects start on wp and only move away once scale forces the decision