You should be using Google Photos
Over the past decade, Google has released a number of "dud" products, but some of those products lead to awesome additions in other ways.
The oldest example is with Google Wave, the "email replacement" collaboration tool. It never took off and is long dead, but brought the amazing real-time "everybody type at the same time in the same document" features to Google Docs.
Another Google product has a similar history. While Google+ isn't completely dead yet, it's been scaled back a lot and will never be as big as Google once hoped. However, inside of Google+ was a brilliant photo system that is a standalone product you should all be using -- Google Photos. Here's why:
Free
First, it's free for unlimited photos. You're "limited" to 15 megapixel images, but that's more than enough for anyone but the most serious photographer. My wife has more than 50,000 images in Google Photos and it doesn't cost us a cent.
Cross-platform
It works on most major platforms. It's available for iPhone, Android and you can browse it on the web from any computer. This also means that if you change phones (whether it's another iPhone/Android, or if you switch platforms completely) all of your photos are perfectly safe.
Auto-upload
On your phone you can set it to automatically upload all of your new photos and videos. Better yet, you can tell it to only upload when you're on wifi so that it doesn't use up your data.
Free up space
Since Google automatically uploads all of your photos to the web, you don't necessarily need to keep them on your phone eating up space. In late 2015 they added a simple option to "free up space", which will delete every photo from your phone that has already been safely backed up. This Lifehacker post explains it further in-depth.
Assistant
They have a fun feature in the Google Photos assistant (formerly called "auto-awesome") that does neat things with your photos. For example I shot a series of still photos in burst mode, and Google automatically put them together into an animation:
Easy to leave
Last, it's easy to leave. As I explained in my Brand Loyalty is a Bad Thing post, Google makes it easy to leave. If you decide there is a better solution out there, you can head over to Google Takeout and download all of your photos in one shot. Google Photos is an amazing product that I'll likely continue to use for a long time, but I appreciate that they make it easy to leave if you find something better.
Do you use Google Photos for your images? If not, what do you prefer?