I'd say The Sentinel has more drama, and atmosphere, also different textures, with that calm threatening part.
But Glenn's Painkiller solo with that tremendous rhythm under and next (K.K.'s rhythm guitar is f**ckin' awesome) to it is so mindboggling cool. Love the vocals, they fit so well with the aggression. Still, the song maintains melodic. Best combination of melody and aggression. Ever.
Not my favourite Priest song though.