Lets cut to the chase: As you all probably can and should tell by now, I'm more into the darker characters like Ghost Rider, The Punisher, Blade,ect.
The darker characters need more love not just from the film makers and critics but fans as well. Their not as well known because their not geared towards every one, well Black Panther is somewhat well known outside comic fans and Ghost Rider has became some what a house hold name after the apocolyptic disaster Mark Steven Johnson created (though it was still faithful to the comics).
The Punisher needs to be more appreciated because the character is very interesting and unique. He may be up there with Blade as far as the least family oriented superhero ever created but he's as real as your gonna get, he has some very interesting stories and 2 of his 3 movies weren't bad. The original Punisher film was pretty good for what they could do at the time, 2004's Thomas Jane remake is the best and stayed true to the comics and who the character is in my opinion. He was a tortured soul, who is still grieving on the death of his family and in trying to create a better world and do his family justice he cleans the streets of mobs and gangs. Basically he is the non kid friendly version of Batman.
Blade: I'll be honest, I never read a Blade comic. But let's be real. It's because of the Blade films that lesser known characters got movies and it showed that darker heros can have success at the box office too. He is the first success Marvel had and whether or not the films had a Marvel Knights logo attached or not, Blade is the start of the Marvel Knights movies and basically even though he is a vampire hunter, he is greatly under appriciated and if it wasn't for the films he never would've been as popular as he is today. He is under appreciated because his stories and his character deals with vampires. I think he deserves more respect then he gets.
Ghost Rider: Now this character has become a punch line like Nicolas Cage's career since Mark Steven Johnson destroyed them both. Though the film was respectfully close to the comics, it was still in a way original. The comics have great stories but again being a darker character he doesn't get the respect he deserves. The newest Ghost Rider film, Ghost Rider: Spirit of Vengeance for most people made it worse though I greatly enjoyed it. He is under appreciated because he deals with the great fantasy of demons and the way he's been represented since 2007. Also due to everyone for some reason hating Nicolas Cage.
DareDevil: Now we all can agree DD has a couple of the best stories, the most popular being the Born Again storyline. Now his on screen debut was a bit like catwoman only better everything but still shitty, unless you've watched the Director's Cut. Now he's getting his well deserved remake and hopefully done right. This character is greatly under appriciated due to his on screen debut (directed by once again MSJ) and like Ghost Rider, has become a punch line.
Black Panther: Need I say more for him? This character not really being memorable nor having memorable stories still has a decent origin and completely misused. Hell the poor guy has yet to come close to having a debut on the silver screen.
Not a big list but those are the biggies I felt needed focused on, comment if I missed any other dark Marvel characters that have been greatly under appriciated.