Triple H has played the exact same character since 2000, only talking less. Undertaker's character has evolved as a heel dominating in his early days to a face. Then slowly turned back into a heel where he took out McMahon, to Ministry of Darkness which was the epitome of what a heel can be. From there he returned as a face with the ABA and from there turned back heel with the whole Big Evil. Its like Undertaker changes the heel.
Triple H has not changed anything. Trips has been the same for the past decade. Not to take away from his heel run but really... Taker brought something different with his different heel runs. Triple H... whether face or heel played the exact same thing ever since he became "The Game." Taker should be leading now.