Not sure if yer into em, but their heyday was the 80's...ZZ Top has some easy riffs for beginners. Cheap Sunglasses, Under Pressure, and several others are mostly just power chords. As far as Metallica goes, Sanitarium and Fade to Black were my 1st metal songs to learn. But truthfully if you like Slayer, they're surprisingly easier. I've figured out numerous songs of theirs by ear, South of Heaven and Expendable Youth coming to mind. Of course I still couldn't attempt their solos, but if you know power chords, you can probably play most of their albums.