I'm a fan of BunnyCDN - somehow they're one of the fastest while also being one of the cheapest, and they're based in Europe (Slovenia).
KeyCDN is good too, and they're also Europe-based (Switzerland), but they have a higher minimum monthly spend of $4 instead of $1 at Bunny.
Fastly have a free tier with 100GB per month, but bandwidth pricing is noticeably higher than Bunny and KeyCDN once you exceed that.
https://www.cdnperf.com/ is useful for comparing performance. They don't list every CDN though.
Some CDN providers are focused only on large enterprise customers, and it shows in their pricing.