I Used to Hate Caching Plugins!
I would research and tweak my .htaccess rules which was great for a while because my websites were lean in the first place. Not too many plugins. well designed themes. All of my sites were pretty fast.
About 5 or 6 years ago I tried Super Cache and after that W3 Total Cache, while they both worked they caused problems on some of my sites so I went back to using no caching plugins at all.
About 3 years ago 1.5 second load time became the definition for a "fast loading website" so I decided to consider caching again. So I tested Hummingbird by the folks at WPMU Dev. It is a good plugin but I wanted to check out some others.
Testing WP Rocket
What a difference! I was very, very happy. Like most caching plugins for you to get the most out of it you need to configure it and test your settings. You might exclude some pages from the cache like a shopping cart checkout page or a contact form (unless it uses Ajax).
If your sites are lean to begin with you can use fairly aggressive settings. You should make sure that your hosting environment is set up correctly and that you are using a more recent version of PHP. Also it is critical that you optimize your images and use appropriately sized images.
Why Free Caching Plugins are Not for Me
The number one reason I don't use Free caching plugins is customer support. WP Rocket has excellent customer support.
Secondly free plugins are not tested as thoroughly and often do not include some of the advanced features that WP Rocket does.
Finally, as a web developer who provides customer support to clients after a website is complete I insist on the best in class tools. Often those tools (be it themes, plugins or even hosting) cost a bit extra. WP Rocket is the best in its class.
Yes this the image link above is an affiliate link, but, I only recommend products that I'm actively using and have tested thoroughly. I use WP Rocket on all the sites I create.