So far you have convinced me to go to the cinema to watch something
Well, no promises. I haven't seen it yet. But IMO Benedict Cumberbatch is a good actor, so that should help.
I'd agree, the Fantastic Four are one of Marvel's weaker groups. That said, Marvel characters tend to be more interesting than DC.
guidance regarding proper superheroes
Hm. I'm anxious to recommend, when I have no idea how much what you find interesting lines up with what I do. Hollywood in general is terribly lacking in creativity, and there aren't many indie superhero films, and certainly none for Marvel or DC. But I'll give it a shot.
I thought the new Ant Man movie was really good. I went in expecting it to be mediocre, and it was fantastic. Especially if you like millenial snarky dialogue. I don't know anything about the Ant Man comics, though. In the movie, the character development wasn't off-the-charts, but there was a good bit of redemptiveness. It was especially good if you like the type of science fiction that describes how things work (like The Martian). They spent some time going over how all the Ant Man technology worked, both the shrinking and the controlling of ants, which I enjoyed. If you like that kind of thing.
As my Superman rant mentions, Justice League Batman is good, if you like that kind of explaining applied to tactics. There haven't been any good Justice League live-action movies, though there are a few decent animated ones. Justice League: Crisis on Two Earths and Justice League: The Flashpoint Paradox.
I don't know which movies you've seen... I like Iron Man, as I said, for his arrogance combined with his mechanical genius (I'm an engineer). It makes him an interesting anti-hero. And Robert Downey Jr does an excellent job portraying that character.
In Guardians of the Galaxy, Chris Pratt also does a great job portraying the goofy-but-virtuous Star Lord. It isn't really true to the comic character, but if you're looking for movies, it's a good character in itself. The other characters in Guardians are relatively deep as well. Rocket Raccoon has a fantastic backstory which they only skim the surface of, and which significantly shapes his character (which the movie does portray well). I'm hoping we'll see more of it in Guardians 2 next year. Likewise, Star Lord has a lot of backstory yet to be covered, that Guardians 1 did a good job introducing.
Green Lantern is one of my favorite DC characters; but don't see the live-action movie. It's terrible. If you really want a movie to redeem DC, there are several animated Green Lantern films which are okay, one with the Green Lantern's backstory, and one about non-human Green Lanterns and the history of that universe (Green Lantern: Emerald Knights).
The Daredevil character is good too, but the 2003 movie only did a mediocre job presenting him. I've heard the new TV series is good, but I haven't seen it, so I can't say.
Mystery Men is good. It's a 1999 indie superhero comedy, about a team of misfits with janky powers. I found it funny enough, as well as doing a good job realising the struggles of misfits and nerds, and how they grow, learn from each other, learn to get along, etc. As a nerd myself, I found it relatable.
If you're open to graphic novels, I highly recommend Superman: Red Son. It's an alternate universe where Superman's baby spaceship lands in the USSR instead of the US. It's a great "what if", where Superman's innate goodness is combined with Communist upbringing. It's a fascinating though experiment, and does a great job redeeming an otherwise dreadful franchise.
On the subject of graphic novels: Neil Gaiman's Sandman is also phenomenal (as are the offshoot novellas about Death). Sandman takes place in the Marvel universe, but the Marvel superheroes have almost no part in it. It's a massive exploration of the life and psyche of Dream, one of the foundational deities of that universe. Dream's sister Death is another foundational-deity, and almost as interesting as the main character.
You may have noticed a trend: DC animated movies tend to be much better than their live action ones. Marvel are reversed; I can't think of a single animated Marvel movie worth watching. The 2007 Doctor Strange possibly being the exception.
There's also a radical difference in screen and comic depth. Most comic books have exponentially more depth than films. For example, the many Wolverine movies show off just how much depth there is to his character, but they're only mediocre at presenting it. Marvel has poured an incredible amount of depth and history into that one character. Actually, all the X-Men have deep backgrounds and characters, but there are so many, the films don't have time to go into any of them.
I like superheroes for the same reason I like any mythology: they personify our humanity. Everything that makes us human, is personified and clarified into singular characters: hopes and fears and dreams; virtues, and vices, selfishness and charity. Everything that makes us human, distilled and bottled and written down, for ourselves and others, to read and understand, and hopefully use and learn from, to live better.