I thought the Pulaski/Data relationship developed very well.
Data was treated as a machine by Pulaski at first (gosh, he was
a machine!), but from Unnatural Selection onwards you could see a mutual respect. Watch episodes like Pen Pals and Peak Performance. If Muldaur had stayed on in season 3, we would have seen a further development Im sure.
Was sad to see her leave. Well, we actually never saw her leave unfortunately.