By all means, keep using Google Photos. It's a fantastic service.
We love the AI-powered image search and face recognition.
But there comes a time in every young Android or adventurous iOS user's life when she tries to download her first Google Photos library.
Surprise!

Google doesn't want you to leave.
Granted, they've provided an export mechanism via Google Takeout that works "ok", but it has a bad habit of stripping date metadata, so the next time you try to sort your images by date....
...all of your "image creation dates" are today!

Don't rent your history.
We have to store our own files, no matter how annoying and expensive.
Our baby photos live in a Synology NAS that's spinning two 6TB WD Red hard drives.
We use RAID 1 for full mirroring. If one drive fails, we can swap it out and the NAS will rebuild the other drive.

Next, you'll download a Desktop App that will enable the Web App to access a folder on your hard drive.

Some folks have massive Google Photos libraries. Those lucky folks will have to leave the Desktop App (often referred to as a "daemon") running for a few days.
The Web App works in two steps.
1. The Web App downloads each and every media item record out of Google Photos. That process usually takes less than 30 minutes.
2. Next, the Web App transfers those records to the Desktop App. This process can take a bit longer, depending on the size of your library; however, the Desktop App can start downloading immediately. It will download whatever records it has and keep looking for more until it runs dry.
We recommend logging back into the Web App every few weeks to download new records.

The Desktop App (aka "The Daemon") has three functions.
1. The Desktop App ingests your photo and video (aka "media item") records from the Web App.
2. Next, the Desktop App starts downloading your "media items". It tags the files with their Google Photos ID. This ID prevents the Desktop App from downloading the same file twice.
3. When the Desktop App restarts, it quickly indexes existing files on your hard drive to see what has already been downloaded. It maintains local records on your filesystem of every file that has been downloaded. If it finds an new file, it first checks to see if it has a Google Photos ID. If so, it can safely skip downloading that file. This process enables you to start and stop the Desktop App as needed. It won't download files twice.