Before the iPhone 7 I always restored my new iPhones from a backup, but I have learned from that 'mistake'. I set up my iPhone 8 Plus as new, to ensure the best experience. It was a painful process to get everything back on it, such as the most needed apps and settings, but I got it done. And I'm happy I did it that way. Because the thing is, every time I restored my new iPhone from a backup, battery life was... just enough actually. I don't know why, but it never lived up to Apple's promises on that one.
Of course I have yet to find out how my iPhone 8 Plus will do, but I'll more than happy if it lasts a full day. And considering it's got a bigger battery, that should not be too much of an issue I think.