For me, it has to be this 'Bam Bam Bam' part at the very beginning of Hilary's Dreamer. I thought it was kinda annoying when I first heard it. Now I'm addicted to this flawless melody

The Sparks hook with the whistling. I hated it at first but it sounds so good now.

I thought the heavy metal lover hook was the laziest piece of **** for the longest time before I saw the light and bop to it now.

I'm listening to that album right now
I've always loved that part in Dreamer!