What’s your recovery needs?

It’s ok to take 6 months to backup to a cloud provider, but do you need all your data to be recovered in a short period of time? If so, cloud isn’t the solution, you’d need a duplicate set of drives nearby (but not close enough for the same flood, fire, etc.

But, if you’re ok waiting for the data to download again (and check the storage provider costs for that specific scenario), then your main factor is how much data changes after that initial 1st upload.