My verdict: the absolute reference for technology targeting, at a premium price.
BuiltWith is very expensive, but offers tons of data on web technologies. The API works super well.
If you really want the cream of the crop and tech data is an essential criterion for your market, it can really be worth testing and investing. It's the absolute reference for technology targeting.
What I like less: pricing is prohibitive for small teams. The interface is dated. It's clearly a tool for established sales teams with significant budgets.
My advice: if you do technology selling (you replace or complement an existing technology), BuiltWith is an investment that pays off. For all other cases, first look at Wappalyzer (much cheaper) and see if it meets your needs.