harddrive formatting for large raid array

New poster here.  I have an 8Tb raid 5 array that is about to be upgraded to a 16tb raid 10.  We have recently run out of space and its to upgrade.  Each single file being copied is between 50gb and 100gb sometimes alittle more.  Anyhow, I have been reading about cluster sizes when formatting.  In this case shoule I format to the highest possible cluster size?  I need as much right performance as I can get due to extremly long write times of each file.  

Btw I have 2 of the systems both are going to be 16TB each and will be identically set up.