The Sims 2, definitely.
The Sims 3 is better for the graphics of the landscape, but the Sims are all so dull and lifeless. Plus, it's better on the Sims 2 that you can't make perfect Sims (unless you use boolProp), at least when it comes to personality. And you can create freaks.
I'd rather have intended dystopias than Sunset *cough*Stepford*cough* Valley. And trust me, I have enough of those.

Sims 2 of course! Sims 3 is is too advanced... I mean it's too alike to real life, so why don't we just go and live our own lives insted?

Sims 2. I think it's harder to create sims in sims 3. All the faces in sims 3 look alike. Anyways, that's my opinion. Plus there's more to do in sims 2. I have pets and my sims are nothing without their pets.

Sims 2. The sims look beautiful in number two if you have the right skins and hairstyles (:
I've played Sims 3 at my cousin's (they own every Sim game ever. Sims 1,2,3 and SimCity) and i am not impressed at all. The sims look blobby and every face is the same! It is also quite complicated! The only great feature is the personality traits, which i wish had been in the Sims 2. After installing World Adventures on my cousins computer, My dissapointment continued.It is a bad rip-off of Bon Voyage, which althought isn't good it is miles better then World Adventures. Shame on you EA!