Are you wanting a watch just for heart rate or are you wanting a watch that can do many other things.
Just for your heart rate, just about any watch that has sensors will do the trick. But if you are looking for a watch that can track your heart rate, count calories, clock time of exercise among other things, there is a "women's watch - IMO". I own one because I read and read about how this watch is top dog for women and nothing is better. HA HA HA!! I can't get this watch to work 100% of the time, usually more than not it isn't worth the trouble of tracking. But I have had it long enough that I have schooled myself how to track my heart rate, I can tell you almost to the number where I am during the workout, so the watch was worth something.
Nike has great watches out there, and I have always thought Nike is the way to go, I just got caught up in how IMO was tailored and advertized for women.
If you are wanting a watch that can track distance, speed of your run, gps of where you are and so one because you enjoy running, Garmin is hands down the best watch out there PERIOD.
It all depends on what you are looking for your watch to do. The Garmin is not a great watch to wear while working out with Cathe although excellent for running, where other watches can do the job of both, just not as much as the Garmin.
Sporting stores are a great place to ask these questions, they know which watch can do what and which one is selling most (most popular because it is most reliable).