Oh, I forgot to mention.
I would strongly advise putting them on a portable hard drive and storing that for the long term. So much can go wrong with the drive not spinning up when you need to recover a backup.
Burning a BD-R or DVD since seperates the recorded medium from the reading device. So if the motor fails, you can just get a new drive.

For my personal photos I have a RAID-1 NAS setup. I wasn't going for speed, so two lowspeed 2-TB drives is a cheap option. Since RAID isn't a backup. I also make two DVD (and more recently BD-R) backups of the photos as well, keeping one copy in my offsite vault (my Mom's house).