My favorites in Sims 4 are Pique Hearth and Rindle Rose. The floor-plans of those two builds can be changed to fit almost any style of architecture. I started to notice that many of the speed build videos were basically variations of either Pique Hearth or Rindle Rose. That's when I started playing around with the floorplans of the two Maxis builds. I recently found that Umbrage Manor isn't too bad either. I'm still working on the floorplan for that one though.
My favorite house in Sims 2 was the Europen Townhouse. I think it was a bin house. It was very small so I used it for university students. It had a flexible floorplan so I was able to expand it as families changed.