[dolmen]

If you are ready to delegate image handling to a SaaS AND do not want bother about it, just use the best one that will allow you to grow in API coverage and volume (number of images, number of derivations, number of clients) so you'll be better covered by an expert in that domain.

A micro API might be useful for a micro project. But if your project is micro, do you really need to bother with one more SaaS dependency? Just use a full SaaS app building platform that will provide a fully integrated developer experience. (https://www.nocode.tech/ is a directory).