I've just about always liked Naruto. He was difficult to take seriously at first, but his comic relief grew on me fast, not to mention how driven and devoted he was. I also liked how tactical he got when things became serious and I'd never see what he was planning to do coming. A great example of that was when he left a paper bomb on Gaara in their fight just before Gaara knocked him away. Hagoromo is right. He does have something about him that draws people, whether it be pity, comic relief, badassery or friendship. He matured in the second half, became less obnoxious and dimwitted and more focused, which was also a great development. His goal to become hokage to get the village that had labeled him a pariah to acknowledge him was compelling, however in the end, he showed he did not have to become hokage for that to happen. He just needed his resolve, hard work and friendship. Naruto had virtually no family or friends at first and he never once complained or caved about it. That's a strong kid. His unknown lineage and Kurama also made him mysterious.
Sasuke wasn't exactly friendly and quite arrogant at first, but I knew right when he introduced himself that something terrible had happened to him and thus became empathetic to his goal. I liked how he softened up after a while and finally befriended and acknowledged not only Naruto and Sakura but other characters as well such as Lee, Gaara, Neji, Shino, etc, not to mention putting his life on the line to save them. His teasing of Itachi made him even more interesting. I also liked that he still acknowledged Naruto in the end in their fight at the valley of death. I have to admit he ticked me off in the Sai arc with his emotionless, ruthless bigot attitude and attacking Naruto. I still can't figure out what he was trying to do. If he was really trying to kill him, possibly because he wanted to rid himself of all humane attachments or if he was just testing Naruto. Sasuke became a hard nut to crack in the second part so I'm not sure. Kishimoto stopped showing his technique development as well in this part, making him even more wonderkind. He gained back my respect however for defeating Orochimaru, refusing to kill anyone for him, releasing his prisoners and forming a new group, as it showed he still cared for people and as one panel eventually showed, his old team. Instead of anger or hate, I felt pity when he attacked Karin, Naruto, Sakura and Kakashi, as I knew he had been influenced and unhinged by Obito's revelations, his new ocular abilities and the people of Konoha mocking the Uchiha. I was glad however to see that Naruto and Itachi could still get through to him and that he finally created a goal above revenge: to save and change the world, albeit still a bit suspicious and mirroring Indra's concept of power to protect the people, rather than love.