Look more carefully at the pricing page. The promo is 500GB for the life of the plan.ibackup looked promising until I got to the page that said 10GB of backup for $10/mo.
I've got a hair over 400GB that is firmly in the "cannot lose" category.
iDrive is another option. https://www.idrive.com/pricing
I'm fairly certain they are the same company. Not sure why they have two separate entities. I use iDrive on my home personal computer and iBackup on my business computers.