I'm considering to use Google Photos as primary storage for my photos, because I use multiple devices, and it makes sense to use centralized cloud service.
I really don't like an idea to have have by photos stored only at one place. And, I want to have local backups of my photos (on external HDD).
Downloading few GBs of same photos regularly doesn't make much sense. Therefore I consider to make incremental regular backups (photos uploaded in past N-days/N-weeks), and only occasionally full backups.
Requirements - supported platforms: both Windows and Linux, or directly from web (no native application, works on all platforms)