There is really only one rule when it comes to storage: have more than one copy. Everything man namde can fail in this fallen world, so ideally you should have more than one copy on more than one medium in more than one location.
Beyond that it all depends how much you are willing to pay to keep your photos. As @nateb mentioned, cloud storage is certainly an option for one of your copies. Magnetic (rotating) hard drives and solid-state (SSD) drives are other medium options. Cloud storage adds the off-site protection as well, but you could also leave one hard drive backup at a friend’s house and swap drives from time to time.
Personally, I have had drives fail completely, but have not yet (as far as I know) had partially corrupted files except on drives that were about to fail or during transfer, so bit rot is not my biggest concern.