Thanks for the reply!
We need to store 30 GB (safe estimate for 2-3 years) for publicly accessible images and documents. These would be constantly accessed by users. As far as I've measured, this could peak up to 2GiB/hour of network transfer
We also need to store up to hundreds of GBs (but less than a TiB in total) for files related to our server and backups, but these would have slow transfer rates, as they are not meant to be constantly touched. We plan on expanding towards other operations besides merely the wiki, so that would take extra space eventually