Sample sentence:
There's not a dad in the world who compares to you, and there's not a daughter in the universe who's more grateful than (me or I).
Sample sentence:
There's not a dad in the world who compares to you, and there's not a daughter in the universe who's more grateful than (me or I).
There's not a dad in the world who compares to you, and there's not a daughter in the universe who's more grateful than I am.
I is the correct answer. It is actually very easy. To decide, all you do is place, "am" at the end to know. AM is implied. You would not say, "me am", therefore I is correct. Similarly, if the sentence was, "She knows better than I (do)." Do is implied. Another example; "He has the same notebook as I (have)." Have is implied.