I bought a Garmin 305S and have really enjoyed it. Admittedly, I don't use it to it's full potential (mapping courses, etc), but I appreciate being able to download my workouts onto my computer and to be able to see average HR, max HR, times in zones...that sort of thing. The only drawback, and this one really frosts my buns, is that it erases data spontaniously!

Having said that, i have contacted Garmin and they have been quite helpful in tryting to help me find my "lost" data.
It was about $350, which seems like a bit when compared to some other HR monitors, but I would purchase this one again in the future.
Hope that helps!
Ally