What she said in interviews was:

'Let go': 'Losing grip' & 'I am with you'

'Under my skin': 'Together' & 'Slipped away'

'The best damn thing': 'I can do better' & 'Girlfriend'

'Goodbye Lullaby': 'Push' & 'Goodbye'

When it is about 'Complicated', it's a special song to her because it was her first single ever.

Her favorite song ever? hmm...idk! Maybe a song that she has performed on all her concerts.

It seems to me her favorite song is "I'm with you", at least that's what she revealed during various interviews.

I'm not sure, she probably has a lot of favourites. She likes to perform upbeat songs and her favourites from Goodbye Lullaby were Push and Goodbye, I think.

I think her favorite one is conplicated