Metallica is generally good to learn if you want to learn basic metal rhythm - good combination of basic techniques like 8th and 16th note palm-muting riffs, a bit of galloping here and there. (But don't go try Master of Puppets if it's your first month of playing! ).

Nothing Else Matters and Stairway may be a bit tricky though if you're just starting out. Both have a lot of arpeggiated chords that may be difficult to play for new guitarists.

Then again, it all depends on the individual... I remember that when I first started playing guitar, my ultimate goal was to learn how to play Stairway (solo included). Never could get the chord-switching right, my timing was atrocious and the solo was a complete FUBAR... gave up after a while and decided to stick with straight 16th note alternate picking at uber-l33t bpms! Hehe...

damn, brings back memories of the first few struggling months... the first song my friend tried to teach me was Song 2 from Blur...

I was damn blur loh....

Hey... but isn't Cromok like de facto required for all aspiring Mat Rockers?

You're guaranteed to see once in your lifetime some guy sitting on the floor against the wall in a studio with a busted up Kapok playing Another You... clean or not, that's a different story!