I’ve used cloudinary in past projects and am a big fan. It’s very easy to use, and does everything I’ve wanted. The rails gems also make it super easy to upload images (drag and drop, upload before form submit) and add images to any model.
The solution that I’m using now is gem refile by the original author of Carrierwave. Integration with Amazon S3 is easy. Maybe I’ll try Cloudinary in my next app.
Maybe I am old school, but I still use and love Paperclip: https://github.com/thoughtbot/paperclip. Do people need all those other features in those other packages or are they already doing that in iPhone, etc?
Paperclip is easy to normalize photos (sizing, cropping etc) and to setup with S3:
I use Paperclip for both development and production. I missed some documentation, but I have promised top contribute on that this August, so it would be a little easier for others to use.
I like Paperclip because it is a lightweight gem that does one thing great.