You mentioned you have 5 X 2tb drives. So between Raid 5,6 and 10, I would rule out Raid 6 as Raid 6 only makes sense from 6+ drives onwards. The less drives you have, the less exposed you are on drive failure.
Between Raid 5 with your 5 x2tb drives that gives you 8TB use able space, as one drive is parity.
Between Raid 10 with you 5x 2TB drives that will give you 4TB Use able, + 1 drive sitting in hot standby. Remember Raid 10 drives are added in the array pool in pairs for Mirror (1) + Stripe (0).
If your drives were each 3tb+ in size I would say Raid 10 all the way...for the reason I'd want my failed drive to be rebuilt within less than 24hours.
Raid 5 with 3tb drives possibly could take close to a day and a half to rebuild.
Remembering while your using 2TB drives, your raid rebuild should be achievable under 24 hours if your using a good raid controlller.
Speede: Raid 10 reads and writes significantly higher than Raid 5.
For your usage requirements.... consider whether space is more important than speed or not. Raid 5 or 10.... is what I recommend to choose between.
Just to repeat : Raid 6 is only beneficial over Raid 5 when your going above 5 disks in the storage pool, and Raid 6 does require a very good raid card as it can be more taxing on the CPU than Raid 5. Anyone with 6 drives or more... I would not recommended Raid 5.
What's my personal choice? For me it's Raid 10.
Raid 5 or 10 for your small requirement...you will be happy.
That's my 2cents from working in storage industry.