App for Cloudflare
This plugin does a lot and is maintained by an active developer. Provides full page caching via Cloudflare for free.
https://wordpress.org/plugins/app-for-cf/
Cloudflare Super Page Cache
A plugin that was sold to Optimole, provides full page caching via Cloudflare for free.
https://wordpress.org/plugins/wp-cloudflare-page-cache/
Flying Press (Paid)
A paid plugin that works well and offers full page caching for free via Cloudflare (New feature)