In some ways Data took over the Spock role in the TNG but he was always his own person, He always wanted to be more human and feel emotions as humans do, which was sort of the opposite to Spock and this made him a very likeable and sometimes humorous character.  The story arc of him understanding human emotions more and more and finally getting his emotion chip was really enjoyable and I loved his cat, Spot, who was not the friendliest creature, but was happy with Data.