Roar vs. Ghost
Legendary Lovers vs. Love Me
Birthday vs. This Moment
Walking on Air vs. Double Rainbow
Unconditionally vs. By The Grace of God
Dark Horse vs. Spiritual
This Is How We Do vs. It Takes Two
International Smile vs. Choose Your Battles

The side with Ghost.

Roar vs. Ghost (the nows after the second chorus are heavenly)
Legendary Lovers vs. Love Me (underrated highlight of a rather stale album)
Birthday vs. This Moment (TM wins because it sounds like M5's Love Somebody)
Walking on Air vs. Double Rainbow (WOA is the album's first moment of grace, and the only Katy song I truly LOVE apart from TD)
Unconditionally vs. By The Grace of God (Uncle keeps losing)
Dark Horse vs. Spiritual (Spiritual is such a nice song to get high to)
This Is How We Do vs. It Takes Two (she wasted her time with these)
International Smile vs. Choose Your Battles (none of them are especial, but they are equally decent on their own)

The second half wins.

I'm on mobile so I'm not doing the track comparisons but #TeamSecondHalf

Second half. The first half is mostly GARBAGE.

The first half has Dark Horse, Legendary Lovers and Unconditionally so that. But the second half shows Katy's growth and it has It Takes Two mmm