I learned the “iPhone photo backup lesson” the hard way a few years ago. At the time I was leaving the company (planned exit) and I need to turn in the company iPhone 4s, I did iTunes backup (encrypted, more on this later) on my PC, as well as on iCloud (paid $20 for 10gb extra space, the free one is 5gb). But where do I get the photos back? At the time I did not know there are software to extract photos out of the iTunes backup. So 6 months later, I bought a new iPhone 5s partly to get my photos back (restore the backup from iCloud to the new iPhone). Btw, this approach is a way described in this osxdaily article. A bit pricy option though.
Until today I need to restore some photos from an iPhone 3g backup, and I tried both the picturescue app (Mac only, $10), and the more pricy option of iPhone Backup Extractor ($30 for home, and $70 for Pro). The difference is the former only extract photos, the latter extracts contacts, SMS, etc. Also the Pro version works with the encrypted iTunes backup.
Online photo storage
My last tip is about online storage of photos. In the past I tried iCloud (paid), Dropbox (free), Google photo (15gb limit for free), Amazon (prime membership, for Fire Phone), and last but not least Microsoft OneDrive. I found OneDrive to be good as I got free space (115gb , among them 100gb is Bing bonus expires on 2/9/2017). So in other words Microsoft is consistent with Google on free space (15gb). I also used Google Photo (google drive) for backup on iPhone too (after returning 4s to employer). But on Google I have 17gb free space. Both Goolge and Microsoft offers $2 ($1.99) a month for 100gb extra space. So this comes at $24 a year. Better than Apple iCloud a few years ago. I don’t like iCloud because it’s not as intuitive as Goolge Photo or OneDrive. And I get to see/browse the photos online via desktop. I think I will stick with OneDrive for a while. One trivia on OneDrive, at one time I tried to back up Apple iPhotos files to OneDrive (about 35gb), it did not work out. One reason being the slow network speed. But I think there might be software related issues too.
PS
One may ask why I resort to the iTunes backup for the photos, and why not directly get it out from the phone. Good question. In this particular case, the iPhone 3g w/ iOS 3.1.2 appears too old for Windows 7 and other OS to recognize as a digital camera. I tried 4, 5 computers (2 Macs and 3 PCs) to this phone and none worked. But the iTunes still works with the iPhone, that’s why I backed up the phone via iTunes and tried this route. So in a word, the photos jumped through the following hoop.
iPhone via iTunes back up => Mac picturescue => photos on Mac => USB stick => Windows PC => OneDrive
The USB stick part is optional, as OneDrive app exists on Mac. I did it because my Mac has smaller disk space than PC.