I would like to see Spidey go back to Marvel Studios because I'm just not excited with what Sony is doing to Spider-Man and his universe isn't really that big and I doubt Sony would ever release a Spidey spin-off film. And I would like to see Fantastic Four go back to Marvel Studios if Fox can't pull off the reboot.
For the X-Men, they should stay with FOX forever!
I fail to see how "Spider-Man and his universe isn't really that big" - just because he's confined to NYC doesn't mean his universe is small. He's got enough of a supporting cast & plenty of villains to keep him busy without crossing over to the Avengers franchise. In my opinion, he has some of the best villains of any Marvel hero - Green Goblin, Hobgoblin, Doc Ock, Venom, Carnage, Lizard, Electro, Rhino, Mysterio, Vulture, Scorpion, Kraven, Kingpin, just to name a few of the most recognizable ones.
Now you're certainly entitled to your opinion in not being excited about what Sony is currently offering, but I just don't see how is universe is small. Personally, I liked TASM a lot and thought Garfield did a great job. I'm looking forward to the next installment and hope Sony continues to put out Spidey films. I've always felt Spider-Man was shoehorned into the Avengers roster solely because he was one of Marvel's most popular characters and not out of any logical reasoning. I'd rather him and his universe be separate from that world... really, the only crossover that I'd be interested in seeing is a Spidey/Daredevil team-up to take down the Kingpin.
When it's all said and done, I think X-Men & Spider-Man are fine where they stand. FF is the property that adds the most to the MCU due to supporting characters that come with it and that's the only franchise that I really want to see back with Marvel.