Yeah its pretty hard to tell. The 03 SCV show was crazy hard for me, but honestly when I watch it now it looks like nothing. A lot of times there's a big difference between how it looks and how difficult it is on the members.
I think blue stars drill looks the most difficult cause besides the ballad they are running around like crazy most sets. Although I'm sure phantom's is pretty tough, having marched myron's drill before.
But that's just me.