There are many types of media, I just use glass beads on everything. I do want to try the black magic stuff or silicon carbide for some projects but its too much work to empty out the cabinet, yeah I know there is a trap door and it all comes out QUICKLY but I just stay with old faithful, glass beads, they were quite well on everything.
For some projects large leaf springs which took forever, a faster cutting media would be nice. But you can't use some of the more agressive media on small aluminium casting like carburator parts. TP tools and Eastwood both have good charts to explain the different ones.