Internal hard drive suggestions

I have mac tower 2x 2.26 ghz quad core running os 10.9.5, I have been using the owc mercury elite pro qx2 raids with 4 seagate barracuda 2tb drives each. I have a full season of 23 one hour 6 camera shows that I need constant access to, along with multitude of other projects. So, in other words, I need a ton of storage. I have been having problems with some of the seagate drives going down. I get error message that they cannot be fixed.
What would be your suggestion for the least expensive option for storage. I do like the raids, what is the best recommended HDD to put in them. The SSD are a bit out of my price range, if I don't really need them. It is reliability over speed that I care about. What about the hybrid SSD.
Thanks for any suggestions,
George McMorrow
cinecall productions

Thanks Christoph