Depends on the details. For example, AWS Glacier may be cheaper than S3, depending on the frequency the images get accessed (it probably won’t be best for you, but there’s a possibility that a mix of S3 and Glacier fits your use case better than putting everything in S3)
Glacier certainly will be slower, though.
You also may have requirements w.r.t. access time, may want a search facility, may want the ability to serve multiple image sizes, may have legal requirements such as the GDPR, copyrights that differ across the world, etc.
I would probably suggest S3 infrequent access tier. It’s a little more expensive than glacier but quicker restore times. I figure if I need access to these photos I can wait an hour or whatever.
If you can’t decide, AWS has Intelligent tier now which will decide which storage type is appropriate based on your usage.
I store about 200gb of photos up in S3 and it’s roughly $.49/month
that's a terrific deal.
I am assuming that's glacier tho, because seems like the even the infrequent s3 would be around 2.5
From AWS (this is assuming no transfer):
200 S3 IA Storage x 0.0125 USD = 2.50 USD (S3 IA storage cost)
S3 Standard - Infrequent Access (S3 Standard-IA) cost (monthly): 2.50 USD
How often?
What size?
From where?
Do the missiles launch on failure to serve an image?
How much are you willing to spend?
When do you need it?
For how long?
Obviously, I am assuming it's an engineering problem.