So my computer crashed like 3 days ago and ALL my CC was just wiped out. Along with all my saved games..not to mention my documents and pictures.

I don't really want to dig through the internet again so I'm here to ask what is some of your favorite hairs/skins/clothes/sliders/etc you just have to have?

Hm, I tend to accumulate every slider I come across. Euromutt has some really good ones, and the ones by le.Wing here are pretty good as well (they're body sliders, so they really add some variety to you Sims).

But thus far slider's are all I've found that I really have to have.

A good chunk of the NRaas mods. Master Controller and Traveler especially.

Agreed with above, NRaas mods are lifesavers. I have numerous amounts of favorite hairs and clothing I got, majority are ones I found off of tumblr blogs and The Sims Resource. My sims looked so bad before I found how to put custom content in my game, lol.

Nraas. Pretty much all of it. Error Trap and Overwatch especially though to catch/fix game breaking bugs. Cyber Bobs cursors for visually impaired simmers because even if you aren't visually impaired it can be hard to see cursors over snow. Mods to get rid of route fail animations. Shimrod's Townies out on the town to keep various places occupied when your sim wants to go out and mingle. Twoftmamma's routing fixes. Ellacharmed's fixed worlds . . .

Nraas Mods of course :D
And some great mod from this site like Buzzler's Moar Interaction

No Intro mods, deco and stencil remover, Icarus' food mods, Buzzler's housekeeping for everyone and no more restriction choker, just about all of the Nraas mods, and CycloneSue's stick fences

Lighting mods! Burntwaffles has some really nice ones.

Fanaskher's hair retextures, Brntwaffles' 2T3 conversion of Charlotte's clear eyes and Kurasoberina's Starfruit skin.

CC hair and skins and eyes--they make the Sim! I usually try to see what photos of Sims I like on this site or around and then get that CC. You could start with MTS Top Items category.