User blog comment:CallMeKnuckles/DEATH BATTLE Prediction Blog: Natsu VS Ace/@comment-26184007-20170419144919/@comment-26184007-20170424125434

So overall what Ace has is the Flame-Flame Fruit that allow to control and become fire, which Natsu could counter since he eats fire. Even if Ace turns into fire, he's still technically generating fire so Natsu could eat some of Ace's fire if Ace tries to form into fire. Comparing both characters fighting skills, Natsu has many different abilities ,besides using fire, I see him use a lot more Hand to Hand combat than Ace does. Natsu can pull out situations to do something in almost impossible standards. Ace however relies on flames more than using hand to hand combat. Ace may have conquerer haki, but he doesn't seem to use it besides at young age. Also conquerer haki wouldn't work on Natsu because Natsu has always shown high willpower.

Again, my winner is Natsu Dragneel.