The Sims Resource still has a large amount of Sims content from 2 and 3 as well as 4. Modthesims.info too. I know its getting harder and harder to find stuff but those two places still have it and are both large collections of creators from the community. Many of their creators have (or had) their own sites too, that have since (in some cases) closed, but the content remains on TSR and MTS. Its not everything there is, but its a start for anyone still hunting.