No. 3: Wolverine & Spiderman

Credit: Marvel Comics
Peter and Logan have an interesting relationship to say the least. Though you probably wouldn't think that an angry old mutant with a horrible past and a nerdy high schooler would be friends. Even so, the two heroes act more like brothers than anything else (mostly because Peter can't keep his mouth shut), but no matter what they respect each other and would surely call each other friends (just never expect either of them to say that out loud). Logan is one of the few Marvel characters who gives Peter legitimate props on how heroic he is, which encourages readers follow this bromance as much as they can.
Though these two seem very different they've actually been more similar than people think. Even with Spiderman's no-kill rule and Wolverines pension for doing just the opposite, the two are best of buds. They also have a ton of mutual friends, having both being apart of the Avengers and the X-Men (Spiderman was a X-Man for a short time) and have dated some of the same women too. Their series Astonishing Spiderman & Wolverine cements just how much the writers at Marvel try and show this great bromance.
Heck Logan has even been to dinner at his Aunt May's house. How many of Peter's girlfriends can say that?