My website of choice is TSR (the Sims resource). People often advise against it, it's a bad website if you don't buy a VIP account. Without a VIP account you'll have to wait 10 seconds before you can download an item.
However I am on a very very slow internet connection at home, which makes it troublesome for me to browse through often very graphically intensive websites and tumblr blogs of CC creators. Using the TSR basket function is the only way for me to get a good amount CC without a lot of loading time (ironically).
There is a lot of bad CC on TSR though, so I feel you need a bit of an eye for spotting which CC will look nice in your game and which will look bad.