You really hate that franchise! X1/X2, First Class, Days of Futures Past and Logan all justify its former existence.
Definitely uneven, but as per multi-verses go you can pluck out a couple of elements and essentially ignore the rest.
I don't hate the franchise overall and I certainly have enjoyed some of the films. What I do hate is that it did a crappy job of portraying the X-Men as a group and particularly did many characters real dirty. First Class was the only one that was remotely a good characterization of how they are a family of outsiders and it ironically featured few of the main X-Men. So I'd characterize the franchise as some "good and entertaining
superhero films" but "lousy
X-Men films". I want to see the X-Men done right in the MCU and it would be hard to do with any of that baggage from Fox.
I also hated out it basically centered on Wolverine (a character I'm actually kinda meh on despite his popularity) and way too often went to the Xavier/Magneto frenemy well. The last thing I want is to see those big name actors brought back overshadowing all the other characters that still haven’t gotten to shine.
On top of that, the timeline in that series is so messed up that trying to do any linking to those stories unnecessarily complicates the MCU. I don't see how you can effectively bring in elements from the Fox universe without bringing in the bad stuff too.
Whatever they do end up doing with Xmen (and by no means do I think they are totally going to keep the majority of the former cast), we can't have a third take on its origin. Magneto particularly is now problematic, the whole shtick is he's a holocaust survivor. We're too removed from that to involve him in the current day MCU because I think the MCU is essentially caught up to our current year with the five year jump again.
I don't feel we need to have any origin story per se. It's fine to start them off already in action like they did with Spider-Man. But I do really want to see it be a team of equals who are outsiders - I'd love to start out with maybe the original five (Cyclops, Marvel Girl, Beast, Iceman, Angel) maybe with Storm as well (could use some diversity certainly) and actually develop all of them as people, which never really happened in the Foxverse.
As for Magneto, we've had him so much already that I don't see a problem with cooling him off and going with other villains. He's not the only person the X-Men have ever battled. If they bring him back, maybe they'd refit his origin to being the first mutant used in the slave camps on Genosha or something like that which would keep the same basic concept but reframe it to a more reasonable timeframe. Or since time travel is a thing, they could have him be plucked out of time to the current day if needed and still use the Holocaust origin.
As an aside, I don't have a problem with using the Multi-verse as a way to bring in mutants (could be used to explain why there haven't been any mutants yet that we know of) from another dimension into the mainstream MCU. But I don't want those mutants to be the actors and characters from the Fox X-Men - have them be new people who can be fleshed out without any intanglements.