They both use fire in fighting. Both have some similar attacks. But, there has to be only one winner. I, go with Natsu. So, I am going to explain him. I would explain Tsuna but I hear people say he is a Fire type and I don't really know him.
Natsu gained lighting from Laxus during the fight Fairy Tail had against the 2nd guild master, Hades. He cut an entire forest using only one move with lighting and it's called Hammer of The Lighting-flame dragon.
Natsu can also melt any spell that is on him. During the fight Sting and Rogue vs Gajeel and Natsu, Sting put a spell on Natsu that couldn't make Natsu move. Natsu, melted the spell and was able to move again.
Oh yeah, Dragon Force! Dragon Force is a strong form that only Dragon Slayers have. It is strong that it took Natsu a lot of time to master it for Natsu because it was strong, while Gajeel, Wendy, Sting and the others already did (their dragon force is strong also)
Some of his moves are: 1. Iron Fist of the Fire Dragon! 2. Wing Slash of the Fire Dragon! 3. Roar of the Fire Dragon! 4. Hammer of the Thunder-flame dragon! 5. Talon of the Fire Dragon! 6. Crimson Lotus Phoenix Blade! 7. Planetary Flame, Exploding Flame Edge! 8.Black Fire Dragon Mode, Darkness Phoenix Blade! 9. Black Fire Dragon Mode, Exploding Flame Edge of Darkness! 10. Roar of the Thunder-Flame Dragon! and more but I don't remember and I might have said some wrong so sorry.