Yup, no one's ever going to end the Metallica Vs. Megadeth comparison and stuff.
I say, I like them both, Metallica more in some places, Megadeth more in some places. I say Metallica has catchier choruses, harmonized leads (ie. Puppetz, One, Justice), but Megadeth has more memorable guitar solos, technical riffing, and better solos as well.
I'm still waiting here for Metallica to come to San Diego...then LA!