Raid 1 will be slower because it has to write to 2 hard drives at once but it gives you a backup of the drive in case if 1 fails and reads twice as fast.
In Raid 0 will be fast but completely unreliable, if any hard drive fails complete lost of data.
Mostly, Raiding is just for server environments to improve networked reads and writes through speed and reliability.
Personally, I would leave them separate and possibly mount 1 to a folder of the other.Read this
, It may help your understanding.