Five Magics (it's a coin toss between this and Tornado, but apparently Tornado is better liked...I have no idea why)
Uhhh... amazing main riff, great verses and chorus, interesting lyrics, best Megadeth solo ever? Personally, that's like... my favourite Megadeth song ever.
Anyway, Rust in Peace... Polaris. It's good, but then, the whole album is.