I am looking for a heart monitor with an alert. which one is the best? i need it to measure my heart rate all day everyday. thanks.

Really?: You should only wear a heart monitor if your physician prescribes it. ( And if they had prescribed it you would not be asking this question.) Most monitoring is done for a specific purpose and for limited time. Self monitoring of heart is fraught with difficulty and will require evaluation by a doc anyway. Save yourself trouble and see doc first.