This is often a business decision. Cloudflare's bandwidth is free, and with smart tiered caching my operation serves 6TB a month while only paying out 125gb of AWS egress (with extremely hot files).
Wait can you please elaborate more? I have a site that gets a ton of traffic and my biggest bill is AWS cloudfront bandwidth... how can i reduce this using cloudflare?
Switch out Cloudfront for Cloudflare. Or put it in front of it, if that's what floats your boat.
Well, the currently most used paradigm for building web is that you see the edge servers as your classic web servers and then see the cloud as a service layer. Good for security and scaling. Maybe you can achieve the same thing within AWS.