Jim Johnston has been WWE's composer for music since 1985. Johnston talked about his favorite entrance themes he's created over the years.
In a WWE.com article, in no particular order he gives a list that includes,
"Stone Cold" Steve Austin, Randy Orton, The Prime Time Players, D-Generation X, Hakushi, Ultimate Warrior, Maria, Val Venis, Triple H and The Undertaker.
He talks about how even to this day it still can be challenging.