To easily get your stuff back when an update decides to uninstall everything, you should backup the files in DCCache and Downloads every time you successfully install new downloads.
If you don’t have those files anymore, you will need to redownload them. If you usually move the files to a save place, copy them back into the \theSims3\Downloads and then install. Keep them to 200-500 MB in size, depending on your computer. If the *.ebc/*.dbc files are getting too big, the launcher has new problems.
Accessories is a fifth to me, because even though it has a slightly small role in the young adults looks, it plays a HUGE role in the toddler and childrens looks. Objects is a fourth for me, because I love making my homes beautiful. Hair is a third for the simple fact that I love the styling of custom content hair and that it gives a more realistic look to the sims, and makes each of them more attractive.
Males are too limited and just provide a plain shirt and some random jeans/sometimes shorts. Especially, because maxis clothes are so basic and for females never fit the figure right. Clothes are a close second, because I would absolutely hate to see my sims without cc clothes. And each of my creations has a unique look. it gives a more interesting and dramatic flare to how my sims look.
I like to use the skin details custom content the most.