Which book do you like them together in the most?

<3 them most in catching fire

Catching fire ♥ and in the end of Mockingjay :))

Mockingjay because katniss doesn't finally fall in love with him til Tue end of it

Catching Fire. I like the part when they're on watch on the beach and they were kissing and stuffs!

I loved katniss and peeta in catchingfire the most because they seemed really in love even though katniss technically wasn't in love with peeta. I just wish that the rebels would've saved peeta when they saved katniss.
<3 katniss and peeta 4 ever <3

Catching Fire, definitely.
In THG, Peeta was already in love with Katniss, but she was faking it almost all the time. And Mockingjay is too sad with the hijacking.
In Catching Fire though, Katniss begins to fall for Peeta for real, and we have scenes like her reaction to him nearly dying and the beach scene.