Storage raid - 4 x 3 TB disks

I am quite new in the proxmox business - but have played around with it for a week now, and I'm impressed.
I have installed Proxmox on a 256 GB SSD, working fine - but how do I implement my 3 TB disks as storage?

RAID-1 so I have 2 pairs of 3 TB storage?
RAID-5 which gives me 9 TB storage?
RAID-10 perhaps?

and how to implement this i Proxmox:

As directory storage?
As LVM storage?

Any suggestions?