Honestly, I don't think this rings true anymore. Google's search quality has significantly dropped. I was astonished when someone brought up Google: there were four(!) ads in the SERP, disguised as organic results.
The actual results, the organic ones, are very similar to DuckDuckGo[0] too. I've been using DDG for a long while now. Great search engine.
FF puts ads in the page you start on. There's no ads on Chrome when you open a new tab, the default page when it starts up, etc... No ads in the UI. And when you pay for things, no ads. No ads in my Gmail, on my Youtube (yes I pay for Premium), etc... Versus other companies that'll put ads in paid products (MS, Samsung, others).
Firefox's new tab page mechanism seems to recommend very suspicious insurance schemes too. Do they vet what they advertise? Actually, as an off-topic thing, how would you even advertise on FF?
"Google is still the best search engine" And the same place where you get 1 page of ads for simple search.
Looks you are contradicting...