I think you need to treat "commonly searched" and "commonly hit by users while browsing" very differently. It's not popularity of searching or articles written about a CDN that determines the cache hits.
Google search can only tell you how popular something is to search and how much content there is about it. They aren't going to be showing you a website just because there's a src="cdn.example.com" in the code, only if it's in the text.
To actually know then you either need them to report their # of users and trust them, or scrape tons of websites and check their source for which CDN they use.
You may be right that CDNJS is more likely to result in cache hits, it's just that none of these figures actually help in finding out the answer.
CDNJS being in 1000 small github blogs could easily be less impactful than a single large website using jsDelivr. We have no idea if the github projects are even used.
Again, it may well be the case that it's better in this way, but these figures show nothing really either way.
Here's a bit of an attempt at looking more at it, though I don't know their methodology:
This isn't some game to win, I wanted to show that there may be more useful metrics that correspond to what we care about here, and talk of the nuances that might be important. I don't really care who said the right thing first but I do care what the reality is.
We aren't arguing for the contrary. We're just trying to make sure you're evaluating them correctly.
IanCal found some nice links that support your claim, but he even added that depending on what and how you use it, either may be better for you (You wanted to count cache hits).
The thread is about cache hit ratio which is not that simple. A file is either cached at an endpoint or not, regardless of whether it's downloaded once or a billion times. CDNJS only supports ~3k libraries and gets most of its usage from jQuery and FontAwesome.
jsDelivr has an automated backend proxy to support any NPM package, Github repo, or Wordpress.org plugin. It also uses Cloudflare as one of its backends, so at worst it's at parity with CDNJS in cache hits or far better due to more network partners, more global regions, and more packages from more origins.
Anything on CDNJS is also likely cached by jsDelivr, but most of everything cached on jsDelivr is not even available on CDNJS.
CDNJS is only using Cloudflare, JsDelivr has a bigger network with more partners and support for both npm and github.