Another recommendation that you check out DC Rainmaker's site.
I've used a few GPS watches over the years, two Garmins and a Tom Tom. I'm not a huge fan of the heartrate monitoring devices. I just didn't have any faith that the reports were all that useful or accurate (not that I had proof of the latter).
I'm currently using the base model Tom Tom and when it dies I will probably buy another.
Take some time, look at DC Rainmaker's site, work out what features you really want, then go take a look at a few. Not many retail stores stock more than one or two brands/models.
Things that are important to me:
- large numbers on the dial (vital when you're running)
- logical operation for the functions that you'll use
- ease of charging
- ease of data transfer including to sites such as Strava or runkeeper, or that the native app has enough analytical features for you.