My favorite is Deery Meadows if you want to build everything yourself or Redwood Harbor if you want all the rabbit holes and houses already built. The first step is installing an empty world. You could also use this guide if you play with story progression, but want a custom world filled with your own Sims.
In this guide, I use a premade empty world and populate it with Sims for rotational gameplay. This is NOT a tutorial on using Create-a-World (CAW). This is how I setup a custom world in The Sims 3, starting from scratch and building up my world from nothing (similar to my Sims 2 method).
