Both characters and their worlds are "unbelievable". But this much is certain, Thor did a better job of creating it's world/rules and making the audience understand and appreciate them. I don't see how this is deniable.
Both movies are "out there". Thor executed better.
As for Wolverine? Problem with that movie was it was watered down. Jackman was saying we see Wolverine as an animal in all the press interviews before hand. Well, no, he wasn't. He was a *****. He was more of an animal in the X-Men films.
And that is a grave mistake, considering the movie was supposed to be about Logan's conflict, retaining his humanity and not embracing his animal side. Well, what conflict? There was no animal side. How can anyone feel for the character and his plight if his plight wasn't properly portrayed? What they should have done is show Wolverine as a cold blooded killer with the Weapon X team. Show him as a guy who maybe even kills innocent people. But then he grows weary and jaded of all this, and wants to quit. He wants to redeem himself maybe. I don't know, just anything but what we got.
Instead what we got was Logan moping around whilst the likes of Wade and Creed showed that they were the "best at what they do", not Wolverine.