Vanilla wise, Skyrim. Modding wise, Morrowind.
With Skyrim and all of its DLCs+Patches, it is basically a really got mixture of all sorts of things I really like though Skyrim definably isn't perfect and do have its negatives, which other people can point out if they want to... But it is still a good mixture of everything I like... Unlike the previous titles which has something really high on my "dislike list" that I can easily point out.