The Attitude-Era Tombstone was sickening. Nowadays, it's not really that - they forced Undertaker to minimize the risk of a concussion by having place the head way more protectively.
My favorite finishing moves are the ones that can be done at any moment though. Like Sweet Chin Music, RKO, Spear, Codebreaker. We get to see amazing spots with those finishers and the fact that it's pretty sudden, makes it look cool to me. Top-rope finishers are great too. Few thing matches a ladder/on top of cage finisher.