To be honest with you, there isn't a website that actually estimates a worth of any websites accurately, some do estimate way below the worth and some does the opposite. For instance I made a website before and payed around $15 then and didn't do anything at all to it and after a week when I check the worth of it , it was staed on some $37 and on some others $22 which both are wrong so it's useless to depend the worth of any website on any online website worth calculator
A similar thread regarding the worth of this website while back:
https://bitcointalk.org/index.php?topic=1129578.20I agree that it takes more than a formula to estimate a website's worth. I personally would consider criteria like code maintainability, technology stack used, UI/UX apart from the obvious ones like the idea, domain value and traffic.
I believe bitcointalk.org to be worth millions of dollars considering the fact that it is the key player in the crypto currency world while still believing that crypto currency is the Harry Potter of the money world.