This is an insanely difficult question and i don’t think I can really answer it completely because my answer depends on so many things (like who is writing, how the writing is, what’s the story, how I’m feeling today, and who rubbed me the wrong way that day). Regardless, i think it can be brought down to 2 or 3 characters.
The first, Thor. Thor is and has been wonderfully written in the majority of his most recent iterations. While he may seem like a character that is gung-ho to punch people in the face and smack them around with muy muy, he is a lot deeper than that. His undying love for humanity, Earth and is full and complete faith that Loki will do good is just amazing. You really see how much he has developed over the years and has changed from a god to an actual human being. One series in particular is the one where he is morning Steve Roger’s death and you really do see that he always gives honor where honor is due, and then his disdain for Tony Stark is just palpable. Even now he carries himself in the same way (especially with his interactions with Jane Foster) and you realize he is so much more than just a god with a hammer, but someone who is in touch with all facets of his humanity. Great character.
Second, Spider-Man. I know this is played to death, but Peter Parker really does touch you in so many ways. What really get’s me is his self-loathing and there is literally no character in the Marvel Universe that takes on so much pressure from the world and uses it to better himself. There are characters who do hate themselves (namely wolverine), but they really don’t react like Parker at all. He makes each death, each life, each person a part of himself and each new volume you see him dealing with all that pain and smiling in the face of it, trying to better in the face of it and just trying to change for the better. I have full faith that Dan Slott will continue this great legacy. Another good point is that he never let’s his aptitude get to his head and usually puts the world before himself. For example, look at Superior Spider-Man (Spock). Peter could have done everything that Spock had done and ten times that. It has been confirmed time and time again that Peter Parker is smarter than Doctor Octopus, but instead of using his knowledge and abilities for his own benefit, he sacrifices his life, his future, HIS EVERYTHING for the world. He knows that while his own success is important, the people of the world are way more important. His selfless his amazing (plus his commitment to not kill is beyond understanding).
Lasltly, Ultimate Spider-man. Ok now, you may be confused because this is just Spider-Man again, but while you may think so, these are totally different characters. Ultimate Spider-Man has all the same characteristics as 616 Spider-Man, but Ultimate Spider-Man has something that is worlds different…He is only 16. At that age he was a confirmed genius and was not limited to just that. He always used his power for good and he was even more selfless than 616 Spider-Man. How is that even possible? Because he gave up his life (literally) for New York and didn’t even bat an eye at it. He did more than Captain America, Iron Man, Thor, the Fantastic Four and the X-Men combined and you continually see his commitment to heroism not for heroism sake, but he truly believed that he could save the world. His story is just heart wrenching on top of that, I get chills just thinking about it and this past week I just read Ultimate Spider-Man #200 and had to hold back tears…on the bus…going to school. He is literally the best that there is and I really don’t believe anyone else can tell me different. His innocence, his humility, his love for life, his love for his family and just his complete and utter selflessness touch me more than life itself. Miles Morales has really REALLY big shoes to fill, but so far he is going on the right path. So yea…that’s my answer.