To answer your question. Valuate uses Estibot's engine, so they will provide the same results. Estibot states they are quoting motivated end-user buyer pricing.
I forget which site it was, but quite recently Estibot rated a domain at $300. The seller Asked $5000 and got $3000. Now Estibot's value is $3,000. so, in this case it's accurate to 100%. But that's not to say the buyer won't turn around in 2 months and sell it for $5000.
In other cases, say when keywords are reversed (and don't mean much), Estibot is sometimes rating the keywords rather than the order, and can greatly over-estimate the domain value.
These are both examples of how any automated bot can get values askew. Which is why it's always preferable to do some research, at least at NameBio for prices of other recently sold domains.