What Is The Best Platforms For The Most Accurate Comps? (Privy, Propwire, Backflip)?

[Tim Tafel]

I've been experimenting where I will comp the same property with different platforms (Privy, Propwire, and Backflip). The discrepancy so far (5 addresses) has ranged from very little (under $10k) to as far as $100k in difference. Is it that I'm doing something incorrectly? Platforms having different / better or worse / differing amounts of data? Or something else?