I do enjoy the changes they did in X-Men 1 & 2 and The Wolverine. While First Class had a limited time to show certain thing, the changes to Shaw and Magneto being a James Bond type of Nazi killer did work for the movie.
I don't think the real problem in X-Men 3 was comic book accuracy, i know many that were enchanted by the world set in the first and second film but then stoped caring due to Last Stand, i think it mainly had to do with killing so many characters, Cyclops even off-screen, and Jean Grey. May be strange to some fans but many dislike her character,
Last stand wasn't really a bad film but as years passed i came to start to dislike it a lot after discovering Bryan Singer's original vision for the film, the promise of x-3 and 4 shot back-to-back as 2 hours long each and serving as the conclusion to the saga, with x-3 being Phoenix saga and x-4 being an end to the long x-men/ Magneto seemed a lot more promising than what we got.
I think what hurts the x-men films is the lack of focus, Last stand was advertised and done to be the final film of the trilogy, yet it left so many strands open that it felt like a cliffhanger. With X-Men Origins they weren't even sure what to do with the series, it was supposed to be a new series of films but they didn't know where to take it from there. The 3 post-credits scenes are a good example, let's see:
1- Wolverine in a Japanese bar: It could have happened, but it seems like he didn't do much there since his major story in Japan was shown in The Wolverine, and he's dragged there with a big beard and all.
2- Striker is wanted for interrogation because he killed an officers with a bigger rank, was that even necessary? What were they expecting that to lead? A William Stryker spin-off? in x-2 he's easily talking with the presidente
3- Deadpool finds his head and can now open his mouth, from what we were told the Deadpool spin-off is going to be set in a different universe, so this also leads into a dead end
X-Men Origins: Wolverine was bits of plot trying to become a single story, and that was the problem. The last act was really jumping the shark, i mean, look at this:
It's not even about f*** over deadpool, the idea itself is dumb, when i was like 6 years old and was very into x-men i remember thinking about something like this, a sword as claws or something like that, but even then i found it too stupid since it would enable the character to move his arms.
I'm glad Bryan Singer is back in control, and FOX is trusting more in their directors and creative minds, i don't agree about puting the Fantastic Four reboot in that universe, it doesn''t really fit well, but they have a lot in the X-Men franchise to make an expansive franchise of their oun, that is if they want to follow the Marvel Cinematic Universe example