1. Kinkaku & Ginkaku. Reason: Based on their track record and ages, they fought together longer than other ones. And basically because their teamwork was flawless...even in death.
2. Naruto x Hinata. Reason: Excluding ch. 700, all of the previous adult pairings only showed how they met and what was basically the final moments of the pairing. The progression in Naruto and Hinata's relationship was more detailed than that, and the bond went beyond superficial aesthetics such as somebody's physical appearance.
3. Naruto. Reason: all of the effort he went through to bring Sasuke back to Konoha despite everything that was being said/done says enough.
4. Hashirama & Madara. Reason: not to dump on anyone else's friendship, but i haven't seen any in the story that was as unique as theirs' to be able to survive the differences they had.