On my iPhone I have these apps for running, Nike+ GPS, miCoach, Nike+ iPod and RunKeeper.
I haven’t gone back to any of these app since I found iSmoothRun. It isn’t just that it’s the best, it gets updated quickly and new features keep coming.
Now (Oops, I should say very soon because I’m using beta) you can select up to 4 data (cadence, heart rate, altitude, pace) to display at the same time.
What is best is that the data you hard earned is always there in your hand, no internet access to a website is required.