Metronome vs. drum machine

[mtlin]

Is it better to practice with a metronome or a drum machine? When I practice with a metronome, I set the click for the 2 and the 4. Here are advantages of each as I see them.

Metronome advantage: Clicks on the 2 and 4 make you keep time more and rely on the metronome less.

Drum machine advantage: Better simulates real world playing conditions. Playing with real drum beats gives you practice fitting guitar parts in with drum parts.

What do you think?