I've tried them all and nothing beats the good old garmin. However, speedcoach, is a great app that actually uses the phones motion detector to determine cadence ... i liked it at first then got bored with it. I now use RunKeeper to feed intervals and current speed each 30 seconds to me through earphones, and my garmin to record the journey, heart rate etc. I also bought a Wahoo Fisca ANT attachment which makes gps and heart rate detectable on the phone.