Incidentally, evaluating an image CDN is my current task at $dayjob. I've been comparing uptimes and, with the caveat that this data is not easy to gather and harder to compare across providers, I just noticed that imgix had twenty-five incidents the past year, mostly "Elevated Rendering Errors". I take it they're a market leader in the image CDN space but that honestly does not inspire confidence in me. Cheaper providers (Imagekit, Sirv) seem to have better reliability.
(Ofc, another caveat is how accurate do they monitor and report, but---short of running customer sentiment analysis---I don't seem to have a choice other than to assume that factor is roughly equal.)
I guess it's a David-to-Goliath comparison but I would just expect Cloudflare to have better reliability than any of them. Plus, as another reply pointed out, brand recognition helps in getting that budget approval.