The pink Polar F6 is probably the best heart rate monitor for women. The f6 is specifically designed to work well in large groups and you dont have to worry about interference from other wireless training gear. This is due to the coded transmission frin the F6 that effectively prevents this sort of crosstalk with other devices. For $105 this is a great deal and highly recommended as the best heart rate monitor for women.

Polar F6 Men's Heart Rate Monitor Watch
Just take a look at these features:
- Full-feature sports watch displays your heart rate, exercise time, and average heart rate
- OwnCode transmitter eliminates interference from other heart rate monitors
- Polar OwnZone helps determine an individual exercise zone; calorie counter and goal management
- OwnCal feature shows your energy expenditure during one exercise session and accumulated expenditure
- Zone Pointer displays your target heart rate zone and where your current heart rate is within that zone

Polar F6 Women's Heart Rate Monitor Watch