I’d go with Ceph and dedicated hardware. Something like Hetzner or Datapacket, or built it yourself and go big with something like SoftIron. We’ve built and maintain a number of these types of clusters - using S3 compatible APIs (CephObjectStore). SoftIron is probably overkill but good lord is it fun to play with that much thruput!

If you’re looking for a partner/consultant to get things going, feel free to reach out! This stuff is sort of our wheelhouse, as me and my co-founder were previously Ops at Imgur, you can imagine the kinds of image hosting problems we’ve seen :P