I'd pick The Drapery Falls because the start is sooo catchy and awesome...
then again... the stupid part of the rap and r'n'b crowd will insist on stopping any Opeth song after a minute or something because they want the catchy part and the singing part to kick in straight away...
If you want to shock... hrrmr... the first few times I listened to When in my headphones the acoustic --> distortion transition scared the shit out of me...