Most of these forms run the same way. An algorithm pulls comparable sales and recorded characteristics, spits out a range, and an agent follows up to convert the range into a listing appointment. That process works fine for a house with no history, but it cannot see a permit pulled last year, a basement developed without one, or a garage rebuilt from the slab up.
The form that is actually different asks to walk the property before it gives you a number. Joel Dyck's hand-reviewed valuation starts from the same sold comparables everyone else uses, then adjusts for the specific improvements an online estimate has no way to detect, which is where most of the disagreement between a form's guess and an actual sale price comes from.
So judge the form by what it asks for, not by how fast it returns a range. A page that only wants your email and address in under 30 seconds is optimizing for the lead. A valuation that wants to see the house is optimizing for the number. Get your hand-reviewed valuation from Joel Dyck.