Clock: iPad wins (uncontested)
Before iOS 6, the iPad had no Clock app -- unlike the iPhone. Now it does, and that's a relief for when I travel, as it gives me an alarm clock I know how to use: no more hoping I figured out the hotel's clock alarm contraption. (Because I'm paranoid, I set it on the iPhone, too.)
You also get a world clock (done very prettily), a timer, and a stopwatch. Those are less useful on an iPad than an iPhone, but it can't hurt to have them.
Metro has no clock app, so you have to use a third-party option, your smartphone, or the hotel alarm clock.