Which is a better crossbow broadhead for Whitetails?

Both will be fine. I use Killzones with good results. Field point accuracy with wicked entry and exits. Your setup will determine how they fly for you.

Started with Shwackers-terrible. Missed first deer due to a blade opening and bolt curved away missing deer by yards. Bow Pro gave me 2 NAP Spitfires to try (What HE took to Africa!) They flew dead-on and I took two deer with them. Last one was a 15 yd. shot from a ground blind and she dropped in her tracks!

I have tried many, I ended up with Spitfires, taken over 20 deer and hogs with them with out a problem .

Ive used Spitfires for years with great success, never tried killzones but they seem like they'd get the job done.

Either would work fine out of a xbow. I have tried and liked Grim Reapers and Rage. Currently I still have the Rage in the quiver since I got a few packs on sale. Shot a buck a few years ago with them and it entered just in front of the shoulder and exited thru the front part of the back ham and still flew another 50 yards. Buck just stood there, didn't know what hit him till he toppled over 10 seconds later.

I used the killzones in my compound. They were very accurate but the one deer I shot with them I never recovered and very little blood even though it passed thru. They have good reviews though. You should always go with what you are confident in.