Cable and Deadpool become this more and more throughout their Cable & Deadpool series.
Before that, Deadpool had this relationship with Bullseye. They took it to the extreme though, where they would try to kill each other and then laugh about it together. When it's all said and done, Bullseye has admitted that Deadpool is the only person he likes.
Deadpool and Taskmaster have also had this type of "friendship"—perhaps said best by Taskmaster: "The things I do for the friends I can't stand..."
Deadpool also becomes Vitriolic Best Buds with Gambit in Mr. and Mrs. X where, despite Gambit disliking Deadpool for kissing Rogue, they have two double page spreads of being Bash Brothers and trade quips at each other.
The Defenders: They are in every way a "non-team" of "non-friends," and the standard Defenders' parting words are "Let's never do this again," but if one of them comes to the group for help, s/he'll get it.
Ben Grimm and Johnny Storm spend most of their time either sniping and snarking at each other, planning increasingly elaborate practical jokes on each other, or lambasting each other with creatively brutal threats about what they'll do to the other (which are hardly ever followed through) after said practical jokes. They are, of course, practically inseparable.
Doctor Doom and Namor the Sub-Mariner. They're both pompous blowhard monarchs who can tolerate very few other people on the planet, and they fight half of the time in the comic series Supervillain Team-Up, but they respect each other as monarchs, and powerful individuals who make hard decisions whereas most people both of them deal with don't rule nations. The only person that comes close to their position is Black Panther but he doesn't share their arrogance.
The Incredible Hulk: An Odd case between Jennifer Walters and Betty Ross. Betty gets along with Jen just fine, but when Betty turns into Red She-Hulk, they start trading insults back and forth.
Wolverine and Spider-Man are a special case of an enduring friendship, arguably due to their moral alignments, but also due to their methods in dealing with people. They butt heads, and fight each other over being two different flavors of an effective hero. Still, Wolverine trusts Spider-Man as one of the few heroes he would never turn his back on; the others are Captain America and Charles Xavier.
The Torch also has a similar relationship with Spider-Man. Spidey and the Torch's team-ups usually consist of them trying to one-up each other, with the expected volley of insults and snark. But at the end of the day, Spider-Man is probably Johnny's closest superhero friend outside of the FF.
Can't forget the Hulk and Spidey. Their team-ups always start off as hostile, Hulk often finds Spider-Man very annoying, and Spidey obviously doesn't approve of Hulk smashing up New York. But after many encounters, they warm to each and Hulk starts saying "Bug-Man is Hulk's Friend", in Secret Wars (1984). In other comics, Hulk even lets Spider-Man take a ride on his shoulders.
But all this pales in comparison to Spider-Man's unsolicited and unwanted "friendship" with Deadpool. Deadpool just loooooooves pressing Spidey's buttons, but will never hesitate to help clean up the messes he starts in Peter's life, and seems genuinely fond of the wall-crawler, sometimes even going out of his way just to hang out with him. Spidey, while forced to admit that Deadpool does have his moments, more often wishes he would just go away.
Michael Morbius and Jack Russell have been friends for a good few decades — a friendship filled with sneering, physical fights and death threats. Still, when it comes to it they won't stop at anything to save each other, sharing a kinship in their respective curses that very few others would understand.
The Ultimates: Monica Chang has this going with Hawkeye a bit.
From the original team, Beast and Iceman, as well as Angel, were vitriolic best buds; they frequently fought over Jean and acted like total kids, and even made fun of Cyclops for being The Stoic.
Santo (Rockslide) treats everyone like this, at least all the staff and students at the Xavier Institute. Anole, Pixie, and Mercury return it with the most obvious friendship.
Hellion. He's a smug, arrogant, self-entitled prick to everyone, including his friends (though less so with Mercury and X-23, with whom he's much less of smartass).
While they're not exactly best buds, Domino and Psylocke have serious shades of this in X-Force.
Domino: Hey, Princess? Shift a little ass, wouldja? We're s'posed to be prepping charges to blow this place. Y'creepy sanctimonious shut-in. Psylocke: Perish in a whirlwind of razors and lemon juice you unbearably perky irritation bomb. Domino: Good to see ya, Bets. Psylocke: You too, Dom.
