It depends on what you value more. Do you want as much storage as possible and not care about redundancy? Then RAID 0 or JBOD would give you a lot of space. I wouldn't recommend it myself but it's an option.

If you care about redundancy but want a good amount of space, you can go with a RAID 5. You'll lose some write performance especially if one of the drives crashes but you won't lose anything.

I would recommend using 2 drives in a RAID 1 for OS and using the other 6 as a RAID 10 for storage. You'll get good performance and redundancy for both storage and the OS.

For a more specific recommendation, more data is needed about your needs.