Not a great builder myself, I guess it depends on what you are looking for. I find Sims 3 easier to use in a lot of respects. Recolouring things is much better and way more fun. Making things match is easier as you can drag colours, parts of patterns and whole patterns onto an object to recolour it. I have managed to do more with sims 3 in terms of building, than I ever did with sims 2 and it has basements in it, so you can build them a lot easier.
In terms of Sims 2, well I never really played sims 2, I used it for creating, I think that creating is easier in Sims 2 than sims 3. It is in some ways an enhanced Sims 2, but game play is better and there are more things you can do with it. I am not sure what others think. There have of course been a lot of bugs in this game and that has been a bit frustrating.
Hope someone else can give you a different view, but have noticed not so many people play sims 3 as they did sims 2.