Out of these options, I went ahead and voted for Daredevil.
I do like Frank Castle/Punisher, Captain America, Black Widow (although ScarJo as her was not who I envisioned for Natasha), War Machine, and Jessica Jones. I also like Vision. He and Scarlet Witch were some of my favorites in the comics.
I'm really excited to see Black Panther (although sad FOX owns X-Men, so I can't see him with Storm, who is one of my all time favorite Marvel characters).
Spider-Man is going to be part of it too now, starting with Civil War. So he's my choice. He's got some of the best villains too. I like Wolverine too but he's not in the MCU. Out of the ones you mentioned, I guess Iron Man.
I'm a huge Spider-Man fan and can't wait for him to join the MCU. I know he won't officially be a part of it until Civil War but I'll vote for him. He's such a compelling character capable of inspiring everyone.
There was one scene in comic books that will always stay with me from Spider-Man. Some people were remarking negatively about how Spider-Man jokes about everything in life and seems to not take anything seriously. He responded by saying something along the lines of how he's been through a lot in life. He's lost a lot of people he loved. He's struggled in life. The reason he cracks so many jokes is because he will always laugh at life right in the face. Life will never beat him down or get to him.
His jokes are pretty much a huge middle finger to the trials and tribulations of life.
Spider-Man is one of the greatest superheroes in comic books in my opinion. It's his mentality not his powers that make him great. He's just a great guy.