How much space needed fo OSMC and Music files?

I have a micro SD card in my PI2. It was originally 32gb and I think that about 24gb is left.
I am looking for recommendations as to where to keep my Music library. I generally would leave all of the SD card alone and let OSMC have it all but I think that my total music library would not be more than 10gb.

My other choices would be an external USB mounted thumb drive or cased hard drive.
I rip the CDs on another PC running Opensuse, and will copy them across the network to whichever device we will choose.

So, what would be your preferences ?
I tried getting NFS to work and gave up after about one day of fumbling here and there.

If I could safely have 10gb of the SD card I think that I would prefer it.
The external hard drive would mean spending some $$$. I have a few 16gb thumb drives laying around.
Thumb drives in my experience have not as good a reliability factor as either the SD or hard drive, so there is that to consider.

So, what do you say ?