It has been a while since I switched from Google Photos, but I've found EZ Gallery to be a good gallery replacement.

For backups, sync your camera roll to a computer/different service. Dropbox can do this, but there are third party apps like Autosync that can sync to a variety of services and protocols. Better than locking it all up in Google anyway.

I need to find one quick. We really use this a lot and auto share all pics between my wife and Is phone. We also really enjoy the auto tagging face feature. That's a must.

Partner sharing, Face tagging, adding photos to albums based on faces.. these things are great. I even enabled the auto add thing on my brother in law's phone because he was notorious for forgetting to share photos of my kids (they spend a lot of time together). So now any time he takes their photos, google photos adds them to my shared album and I have 'Auto save' enabled on my side so those photos get copied into my account automatically.

Also recently Google photos has really done a good job of adding editing features. Ah I really hope Google keeps it going.

OneDrive photos haf an update recently. Looks like it's copying a lot of Google Photos features and UI. Maybe give that a sho