I used Loom to organize and backup all my photos in my iPhone. I loved the service but it got shutdown.
Dropbox purchased Loom and launched Carousel a refined version of Loom. I immediately started using it and have been using it for over a year. The service worked great albite the app was a bit slow but considering I have over 100,000 images that was kind of expected.
But today Dropbox announced that they will be shutting down Carousel as well and that bring us to the best alternative.
I like to have backup of my photos in multiple place it help when situation like this ones happens. So I have been using Google Photos for a couple of months and I was already considering making it my primary service and now Dropbox made that decision easier for me.
So if you are looking for the best alternative to Carousel go grab Google Photos from the App Store its free.