Best way to update and start fresh without losing all data?

[x-evil-x]

I haven’t started from fresh for years and would like to on the X. I have tons of backed messages and iMessages. I don’t mind about losing these but I’d like to keep my app Data. Anyway possibly?
Can I keep all iMessage on my MacBook Pro or do they erase too?

 

[Sharkoneau]

I haven’t started from fresh for years and would like to on the X. I have tons of backed messages and iMessages. I don’t mind about losing these but I’d like to keep my app Data. Anyway possibly?
Can I keep all iMessage on my MacBook Pro or do they erase too?

I've actually never restored as new on my devices, so I can't say for certain there. It does make your job easier given that messages don't matter so much to you; one less variable to worry about.

As for the iMessages on your Mac, those will stay no matter what happens to the phone's software. Ever since I've used Messages, deleting items on either the phone or laptop does not effect the other device. You're in the clear there, unless you'd like to erase them - which you'll have to do manually.