These pairings aren't in any particular order, but these are some of my favorite pairings from all different kinds of anime.
1. HashiMada- My newest OTP from the show Naruto, featuring Hashirama Senju and Madara Uchiha. Seriously, there's so many hints and moments between these two, it's not even funny. It doesn't help that Madara has a slight obsession with Hashirama, going so far as to listen to what he says and do nothing until the real Hashirama faces him. Need I forget how rejected Madara looked when Hashirama said he'd deal with him later.
In my opinion, I think the only reason Madara left is because Hashirama married Mito. That was apparently the last straw for him.
2. SasuNaru- Obviously. As with HashiMada, there are son many hints to this pairing it isn't even funny. Hell, even Crispin Freeman and Naruto's English voice actor pair these two, as well as a designer for Naruto in Japan. Plus, Sasuke was the only person Naruto ever kissed, and vice versa. That alone warrants some proof, even if it was an accident.
3. ObiKaka- The pairing between Obito Uchiha and Kakashi Hatake. This is also a fairly recent pairing and, in my opinion, it makes more sense than KakaIru does. Plus, they are so good together, especially since Obito becomes quite hot when he is an adult.
4. IchiRuki- My main OTP for Bleach. The series goes into so much depth to Rukia and Ichigo's relationship and bond, even making a movie about these two and their unbreakable bond. To me, while Ichihime is one-sided on Orihime's part, while IchiRuki is very much consented by both sides.
5. Ulquihime- My other OTP. Their relationship is very interesting and they do compliment each other well. Orihime, while she is timid around Ichigo, is entirely confident around Ulquiorra and even slaps him when he insults her. Their last moment together pretty much cemented it.
6. HajixSaya- My favorite pairing from Blood+, this pairing is basically canon. Haji is entirely devoted to Saya, even for Chevalier standards. And he even confesses to her before Saya goes into her 30 year hibernation period.
7. TamakixHaruhi- From Ouran High school host club, this pairing is canon to the series, though it is mostly in the manga. They even have a son together in the end. Haruhi and Tamaki go through a lot together and I love them as a pairing.
8. KyoxTohru- Also a canon pairing, this Fruits Basket pairing is my OTP for the series. Tohru loved Kyo unconditionally, despite his faults and Kyo can't help but get quickly attached to her, even early on into the series.
I'll add more later.