I moved from Netlify. The main reasons are DNS and analytics. I already manage all my DNS with Cloudflare, and having everything in the same place is very convenient. Regarding analytics, Cloudflare provides some very basic analytics, which I think are convenient, in Netlify you need to include your own analytics script or use the paid version. I also noticed pages loaded noticeably faster in Cloudflare Pages.
On the other hand, Netlify is specialized in the kind of sites you would host with Cloudflare Pages, so the overall product is more polished towards that. Also, the site build (at least using Hugo) is a lot faster in Netlify. Instant rollbacks in Netlify are wonderful.
Overall, I really like both products a lot and I would not recommend one over the other. It's also important to consider the limits[2-5] of each one. In the free versions, Cloudflare limits by number of builds, Netlify limits the total build minutes. Netlify has a bandwidth limit, Cloudflare does not mention any bandwidth limit.
[0] https://litements.exampl.io/ [1] https://ricardoanderegg.com/ [2] https://www.netlify.com/tos/ [3] https://www.netlify.com/pricing/ [4] https://developers.cloudflare.com/pages/platform/limits [5] https://www.cloudflare.com/plans/