Luffy VS Lucci
No matter how many anime I watch, this will forever be the most epic and memorable fight for me in all of anime history. Luffy literally makes himself a hundred times stronger in such a short amount of time to be able to be on par with the CP9. The way Luffy can fight anyone, anytime, seriously, if its for his nakama. Luffy is willing to do anything to save Robin in the Enies Lobby arc. So much so, to the point he literally fights to his almost death. The thing I love the most about this fight is that just a few simple words from Sogeking give Luffy the strength to fight even harder, finally defeating Rob Lucci.
Naruto VS Pain