Lana's CC Finds - https://sssvitlans.tumblr.com/
Lana's CC Finds has stopped updating as of April 2019, but it has thousands of links to CC for The Sims 2-4. On this CC Finds Blog, you can find tags based on hair, clothing, objects, etc. for easy browsing.
Nolan-Sims CC Finds - https://nolan-sims-ccfinds.tumblr.com/
Nolan-Sims CC Finds offers up-to-date reblogs of various Sims 4 custom content. It also has a handy search function to making cc-finding even easier.
Maxis Match CC World - https://maxismatchccworld.tumblr.com/
Maxis Match CC World stays true to its name and reblogs all Maxis Match Content for the Sims 4.
Xmiramira CC Finds - https://xmiramiraccfinds.tumblr.com/
Xmiramira CC Finds is the Sims 4 CC reblog Tumblr of Xmiramira, creater of The Black Simmer Forum and Facebook Group.