Regardless of whether or not you provide your own SSL certificates, cloudflare still uses their own between their servers and client browsers. So any SSL encrypted traffic is unencrypted at their end before being re-encrypted with your certificate. How can such an entity be trusted?
Cloudflare’s default setup is to proxy your traffic but that’s easily disabled with a click of the admin’s mouse. Of course disabling their proxy service exposes the origin IP’s, server certs, etc. but the point is that you use Cloudflare services the way you want to; it’s not a Boolean “cloudflare or no Cloudflare”.