Personally I use dropbox. Not only its desktop client is super reliable (more so than Google's), it is supported by Office as online storage.
The draw of Google Photos is the free unlimited storage, but it recompresses your photos, even if it is under 16MP. Just try it. A normal 8-16MP is probably a few megabytes. After being "backed up" to Google Photos, it becomes a couple hundred kilobytes. So the free unlimited is really only for super casual users. Once you opted for the full res that is counted against your storage, then flickr is a better deal (1TB for free).