HOLY CRAP, I've been waiting to anaylize this match and I was the first vote for Luffy.
Monkey D. Luffy: I'm NOT counting how many episodes and chapters he's been in. Captain of the Strawhats, ate the Gomu Gomu no Mi as a child, idol is Captain "Red-Haired" Shanks, all his attacks begin with "Gomu Gomu no", he can strech his entire body, has defeated many pirates, marines, and bounty hunters thanks to his nakama as well as his strength, his older brother is Portagas D. Ace, has a bounty of 100,000,000 Beli on his head, loves meat, low intelligence, loves snow, and much more but I have to talk about Franky now.
"Cyborg" Franky: Has only appeared in Water 7 and Eneas Lobby arcs so far. According to chapter 377, he's a Strawhat pirate, known at a young age as Cutty Flam, can build invinciable ships, he's a cyborg who can breath fire, nails, create a shield with his arm, extend him arm using a chain, use his stomach to keep soda cool, and change his legs to become a Centaur, mentor was Tom and he lost him to the Government, has a "family" of people to help him hunt and dismantle ships, has the "Square Sisters" at his side.
You have to admit, Franky is cool. But Luffy is the freaking hero of the story. I voted Luffy.