This is purely IMHO, so take it with a grain of salt.
MET is a good game with great music, but for a rock pin, the audio (callouts) are atrocious. The band sounds bored and it makes me sad to play it. I compare that to AC/DC, in which the developers did an AWESOME job of adding this little "HEY!" callouts and other audio samples that get you pumped up.
For me, ST has a better theme; one good enough that it might help me keep the machine even if it was crappy. The fact that it's also an EXCELLENT pinball machine makes it really easy. And the audio package is generally really good, and will get even better when Stern releases the Bones audio update...