who does cathy say she loves more than herself?

Cathy loves her father more than anyone, that includes herself.

Chapter 22

'I fret about nothing on earth except papa's illness,' answered my companion. 'I care for nothing in comparison with papa. And I'll never - never - oh, never, while I have my senses, do an act or say a word to vex him. I love him better than myself, Ellen; and I know it by this: I pray every night that I may live after him; because I would rather be miserable than that he should be: that proves I love him better than myself.'