Her sex appeal was up front but she was more like Wonder Woman from the start. In the original Claremont Ms. Marvel series she was highly focused on Feminism and being a very active woman who was equal to any man and didn't take s*** from anyone. Promoting her to Captain Marvel was a natural progression, she's been heading in that direction since the early 2000's.
Carol and Peter really should be closer IMO. Didn't they date briefly, post-MJ?
The ones that I can remember are spider-man with punisher and Deadpool. Im not sure that counts as friendship as they only team up before but I would like to think so!
Carol x Peter's friendship has a lot of potential whereby if Peter is in Carol's world, his science background could be expanded upon(in a non-Spidey role). Relationships is all about what could Peter offer Carol to forward the story plot, and vice versa. I would love to see some of Carol's enemies like Doctor Minerva become an anti-hero all because of the Parker Luck...
Felicia should not be one of his best friends, shes a criminal and a shameless sex addict.
Yet, Black Cat become a better person because of Parker. If he had not revealed his ID to Felicia, she might have become a super villain by now. Without knowing Spider-Man's secret, Felicia would have gotten bored and moved on to someone else sooner. Yet Felicia stayed because the writers had a vested interest with the relationship that wasn't going to be a crash and burn moment...
The Fantastic Four, Daredevil, and Black Cat (if she counts) are his closest friendships. Also while he isn't exactly friends with Cap, they have a lot of respect for one another. Their dynamic is similar to Cap's dynamic with Hawkeye. The difference is that Cap probably looks up to Peter a bit more than he does to Clint, and Peter doesn't tease Cap about being an "old man" or act as stubborn as Clint used to.
I think their interactions are fun to watch, but I don't consider them friends by any stretch of the word. They are bound to get on each other's nerves. All the 'friendship' talk writers like to throw around them always felt forced and more of a marketing ploy (especially back when Wolverine was Marvel's #2).
I think they pair up or get stuck enough together that they have a genuine friendship. I think Spider-Man was one of the few major non X-Men related heroes who was shown to mourn Logan's death.
It was basically all of what Astonishing Spider-Man and Wolverine was about.